- For the Supergirl episode, see Alex.
- For the adoptive sister of Kara of Earth-X, see Kara's adoptive sister.
- "It is our job to take risks. We run into the line of fire. We face enemies that no one on this planet has the courage to."
- —Alex to J'onn J'onzz[src]
Dr. Alexandra "Alex" Danvers (born 1989) is a bio-engineer and a top agent of the D.E.O., the daughter of Jeremiah Danvers and Eliza Danvers, the adoptive sister of Kara Danvers and the ex-fiancée of Maggie Sawyer.
Early lifeAlex was born in 1989 in Midvale to her parents; scientists Jeremiah and Eliza Danvers. Since early childhood, she displayed a gifted intellect and attitude towards science, as a teenager she is enrolled in the Midvale Junior High with her adoptive sister obtaining remarkable results. The star of her family, when Kara arrived in 2003 Alex was jealous due to her abilities and was happy when Kara decided not to use her powers. At first envious and ashamed of that "scared girl" who constantly embarrass her in front of her friends, over the years Alex began to deeply love Kara, and acted as her big sister, often comforting her when she was afraid or sad; the bond between the two became so strong that none of them can imagine there lives without the other.
One night, Kara took Alex flying, where the D.E.O. found out about her and forced Alex's father to work for them instead of taking Kara away. One year later, her father "died" protecting a martian, from D.E.O.'s ruthless director Hank Henshaw, but her mother told she and Kara that he was killed in a car crash.
Alex's relationship with Kara was frosty as she blamed her for her dad's death and at school she was considered a popular girl. Unknown to everyone else she had developed a friendship with Kenny Li who was tutoring her. When he was murdered, she and Kara worked together to investigate his death, in which they discovered that Alex's friend Josie was having an affair with their history teacher, which she reported to the officials, but when she and Kara were walking home they were almost killed by whom they thought was the teacher, but when they discovered that Josie was with him at the time of the attack. She spoke to the Sheriff, unknown to her, was the killer and he had her at gunpoint, Alex though showed no fear as she knew that Kara was coming for her, proving herself correct as Kara saved them, making the pair's relationship whole. They also discovered that Kenny had a picture of Kara flying but told no one.Alex's best friend in high school was Vicki Donahue. Alex loved sleeping over at her house; however, when she started to develop feelings toward her friend she felt confused and scared, she began to fight with Vicki over almost everything, even if it was stupid or insignificant, until they just drifted apart. This memory made her feel so bad that she buried it inside of herself for years, consequently not coming out as a lesbian, until much later in life.
Despite her intelligence and academic results, Alex grew up a troubled young adult who used hard-partying and heavy drinking to cope with her latent homosexuality and the loss of her father. In 2013, after a night of drinking and clubbing led to a DUI and her arrest, "Hank" visited Alex in jail and offered her to join the D.E.O., telling her that she was special just like Kara, and that she owed it to her father to be the person he knew she could be.
Working for the D.E.O.
Alex had to go through a full year of training before being allowed to work into the field, but later, despite one of the main reason the D.E.O. hired her was her close connection to Kara, she proved herself as one of the best agents of the agency, quickly becoming "Hank"'s second in command. Eventually she moved to National City alongside her adoptive sister.
In 2015, Alex had to attend a conference in Geneva but the flight 237, on which she was traveling, was sabotaged by Vartox in an attempt to kill her and other D.E.O. agents onboard. Though the plane was saved by Kara from crashing, Alex later berated her sister for doing so, angry that she had revealed herself to the world, and now there is no turning back. Kara was later captured by the D.E.O. and taken back to their base, where Alex revealed her identity as a D.E.O. agent. After Kara was defeated and almost killed by Vartox, Alex rescued her revealing that the only way that the Fort Rozz (prison) escapees could get back at Kara's mother was through her now. She later went to Kara's apartment, apologetically explaining herself, and encouraging Kara to be a hero, the two then went to the D.E.O. base, where they convinced Director "Hank Henshaw" to let Kara defeat Vartox.A week later, Alex along with the rest of the D.E.O., tested the limits of Kara's abilities, firing missiles into the sky at her. Afterward, Alex debated with Kara over the necessity of the tests before Kara had to leave to stop a fire raging at National City Port. Days later, the D.E.O. investigated the theft and murder of a security guard on Plastino Chemicals factory, with Alex calling Supergirl to assist in the investigation. Later at the D.E.O. base in the training room, Alex defeated Kara in a sparring match with the assistance of Kryptonite emitters in the room, in an attempt to prepare Kara for anything she might face. She later came to Kara's apartment and questioned her sister as to whether telling James and Winn her secret identity was a good idea, soon after apologizing to Kara, regretting how she handled things earlier however, Alex was soon called by the D.E.O. who needed her back at the base, telling Kara that she'd call her. At the D.E.O., Alex along with "Henshaw" and Agent Hartmann came to the conclusion that the Hellgrammite was eating the DDT he had been stealing, as the government had been destroying remaining stockpiles, and his food source was shrinking. Later, the D.E.O. set a trap for the Hellgrammite with a truck carrying tanks of DDT, while Alex and Henshaw along with several other D.E.O. agents followed it in another vehicle. The Hellgrammite abducted Alex and takes her to General Astra, who revealed her true identity after she mistaking her for Alura. Alex was later found by Kara who had tracked her down with her super hearing. A fight between Kara and Astra ensued, and Hellgrammit attacked Alex, who tried for radio contact D.E.O., who was able to overcome him by forcing the stinger he protruded from his hand into his heart. Later at the D.E.O. base, Alex was asked by Kara to train her, with Alex promising to make Kara better than herself. Alex then showed Kara a room that had been setup containing an Artificial Intelligence program of Alura that had been sent with her pod. Leaving Kara to talk to it, she thanked "Henshaw" for helping her set up the room.
When Reactron comes to National City with the intention to kill Supergirl as he wanted Superman to suffer and lose everything, Alex decide to help her sister to fight him despite he is not an alien and so none of D.E.O. business. Her stubbornness and determination makes that even "Hank Henshaw" decides to help them.
On Thanksgiving, Kara and Alex are visited by their mother Eliza, with whom Alex had a strained relationship because. since Kara arrived, Eliza expected Alex to protect her, often leading to a fight when she didn't. Alex admitted to her mother that she works at the D.E.O. leading Eliza to told she and Kara how Jeremiah was forced to work for the D.E.O. by Hank Henshaw to protect Kara but was killed in action; never knowing how or why he died. Alex had trouble working with "Hank" after this and enlists the help of Winn to hack into the D.E.O. mainframe to find out what really happened to her father only to discover that Jeremiah Danvers went missing on a mission with Henshaw in South America. Alex and Kara begins to mistrust the director, until an earthquake traps him and Alex at the D.E.O. headquarters with a powerful alien escapee and, while fighting side by side, she found out he is not Hank Henshaw, but a martian named J'onn J'onzz and that her father died protecting him from the real Hank. She and J'onn later disclosed this secret even to Kara.
Dinner with Max
After a Kryptonians attack to Lord Technologies Alex, who over previous investigations has become close with the ambiguous millionaire Maxwell Lord, accepted his invitation to a dinner to interrogate him. After she learned that the appetizer they're eating is actually snail eggs (which cost $ 100 a spoon) she spits them out in a napkin then starts to question him about what were the aliens looking for in his laboratory. Max recalls that Supergirl is also an alien, Alex replied that Supergirl saves lives. Max tells her that she too, saves lives, and asks her what's her real relation to Supergirl, Alex responds him that she works for her organization and she's a reliable employee. Finally Max tells her that they have conducted an inventory in the laboratory and found that the aliens did not take anything, then he proposes a toast to "Alex Danvers, a real hero". Unbeknownst to her, Maxwell planted a recording device in Alex's purse and, later that night, when she goes to Kara's apartment, he overhears their conversation, confirming his suspicions that they're sisters.
After the appearance of Bizarro, Alex goes to Max, saying she knew that he's responsible. Max indirectly confesses his experiments, but threatens Alex to not reveal his operations, insinuating that he knows her family; however Alex orders D.E.O. agents to arrest him and, when he threatened to reveal Supergirl's secret identity, she slams him on a desk and stated no one would hear him, then she brought him to the D.E.O.; J'onn berates Alex for bringing him in, as Max is not an alien, but Alex counters he of all people should understand her desire to protect her family.
Saving KaraWhen Kara is attacked by the "Black Mercy", and plunged into "the perfect dream", in which she appeared on Krypton, Astra came to Alex and told her how to help Kara. Alex with the help of Max Lord, who invented a special helmet, was plunged into Kara's mind to force her to give up illusions. Alex goes through the corridors and find the room where the House of El sits with Kara, who could not remember Alex. She tries to explain to her what is really going on, but she does not believe her and let her being captured and sentenced to the to capital punishment - exile in the Phantom Zone. Alex tells Kara that if she doesn't wake up, they both remain in her mind, until Black Marcy kill them both, while Zor-El tells Kara that once Alex will go, they will be happy again. Alex, weeping, says Kara that she understands how much she has lost and how much she knows Kara wanted to go home, but this is only an illusion. An earthquake begins, Kara realizes the truth, says goodbye to her parents and reach for Alex's hand just in time to avoid being swallowed by a sinkhole. As she wakes up with an expressionless look, Kara demands to know who did this to her, and Alex responds that it was Non.
Killing Astra and recognition of Kara
When Kryptonians gathered to start the next stage of their plan to conquer the Earth, they decided to use the Lord Technologies satellites and connect them to their device. Alex shots Astra from an helicopter and distracts her from the activation of the device. A fight between them ensued despite Alex claiming she did not want to fight Astra, that she know she loves Kara and that she had plenty of opportunities to kill her and Kara, but she didn't, so she offers Astra to surrender. They were interrupted by J'onn who threw Astra away from Alex, and then started a fight with her. As Astra overcome the martian claiming she's going to give him an "honorable death", Alex stabs her in the back with a Kryptonite blade, killing her. After that, J'onn covers Alex to Kara, saying that he killed Astra, because have not seen any other way. Later, Alex asked J'onn why he lied about it and he said it's because she's Kara's hero and he didn't want that to change.
After that, Kara quit working with the D.E.O. because she didn't know how to work with J'onn after what he had done to Astra but, a few days later, she comes back and he tells J'onn and Alex, she's ready to work with them again because it's better for the world. However Alex could not stand it anymore and begins to tell Kara the truth about the murder of Astra, J'onn tries to stop her, but she continued, saying that she saw Astra on him and that he was defenseless, so she had to kill her to save J'onn, who took the blame because he wouldn't Kara to be angry at her. Crying, Alex says that J'onn allowed to do so because they do not want to lose her. Kara hugs Alex. Hank wants to leave, but Kara stops him and takes his hand.
After J'onn is forced to reveal his martian identity to save Alex from Kara (who was under the influence of Red Kryptonite) he was arrested and questioned by Colonel Harper, along with Major Lucy Lane, to find out how he got into D.E.O. and what happened to the real Hank Henshaw. He explained to them that he did not kill Jeremiah Danvers, but they were skeptical about it. J'onn told them about what happened 10 years ago in Peru, about how he met Jeremiah Danvers and how Hank Henshaw tried to kill him. But Harper does not believe him and sends in Project Cadmus both J'onn and Alex, which is accused of complicity and treason as Lucy realized that she knew about J'onn. To save them, Kara is forced to reveal his secret to Lucy, and then asks her to help rescue them. After intercepting the truck in which they are taken to Cadmus, they attack it on board of a pair of motorcycles and set J'onn and Alex free. The martian also sees in Harper's consciousness that Alex's father is still alive and in Cadmus. Alex and J'onn are nevertheless forced to leave National City as fugitives.
After they learn about what is happening in National City, Alex and J'onn went back there to help Kara. However, they are attacked by Indigo, who kidnapped Alex so that Non can later put her under the control of Myriad, forcing her to fight Kara with the intention to kill her. She almost did it, but was stopped by her mother, who told her that she believed in her, snapping her out of the mind control.
Later, Alex told her mother that her father is alive in a secret laboratory, where they will go to save him, after sorted out with Non who, meanwhile, strengthened Myriad's power to kill all the people on Earth. To stop him, Kara decided to carry Fort Rozz (prison), the source of Myriad, into space, however, there she loses consciousness and is rescued by Alex, who drives her back to Earth thanks to the pod on which she arrived twelve years prior. She was later present at Kara's apartment during the celebratory dinner they were having. Thought it was interrupted by a pod flying in the sky catching their attention, causing Kara and J'onn to leave to check it out.
When Superman flew to National City, Alex immediately noticed that there's some tension between him and J'onn, so she tried to find out what happened and discovered that Superman has once helped the D.E.O. uncover an alien asteroid, composed of an emerald-green Kryptonian xenomineral whose radiations weakened Kryptonian's physiology and, despite he asked J'onn to destroy it, the martian refused, deciding to keep the meteorite as a means of protection against other Kryptonians, enraging Superman and leading to the pair falling out. The next day, despite having survived two previous attempts to her life, Lena Luthor, attends to the ceremony to renaming the Luthor Corp into "L-Corp", however, at that moment she began to make her speech, several explosions take place on the site forcing her to flee to a safe place, but John Corben dressed as a policeman, stops her and tries to kill her at the behest of Lex Luthor. Alex intervened and fights him but was ultimately held at gunpoint and taken as a hostage by the hitman; however before he could leave, Lena shot him in the back freeing her.
After Corben resurfaced as the Kryptonite-powered cyborg Metallo, Alex and Winn realized that behind the sample of D.E.O.'s stock of Kryptonite stolen four months ago there is a traitor: J. McGill, who Alex instructed to prepare trucks for transportation of Kryptonite, to caught him red-handed at the time of the abduction. However, before she can arrest him, the agents of Cadmus shot him and knocked down Alex. When she awakes, Alex is approached by the mysterious "Doctor" of Cadmus, who said that if she does not want to join them, she will be killed, however Alex was able to fend off the agents and, after a fight broke out between them, she is saved by Kara. Later, Supergirl and Alex (one in an anti-Kryptonite device and the other in her special exosuit) fought Metallo and together were able to overcome the cyborg, who is ultimately stabbed him in the chest with a piece of pipe by Alex, while Kara held him.
Meeting with Maggie Sawyer
After the assassination attempt on the President, Alex found Detective Sawyer collecting evidence at the airport and asks her what she was doing in her crime scene, Maggie pointed out that she was from NCPD's Science Police and her work is to investigate everything regarding aliens. Alex tried to throw her off the investigation, but Maggie proved herself as the other woman's intellectual match, culminating in an exchange of banter between the two of them that finally ended with Alex sternly asserting herself. The two would later meet again when Alex led her team into a warehouse raid in search of a supposed rogue Kryptonian, in where Maggie was already there, thanks to her street contacts, and casing the edifice from within; Alex's armed gear and team allowed Maggie to discern that the former was in fact D.E.O., much to the agent's chagrin. Later, after being accosted by Kara for going after the kryptonian without her as backup, Alex is invited by Maggie to an alien bar and they tried to figure out where is Mon-El, since they assumed that he is the one who attacked the president. Upon arriving at the bar, the waitress, Darla, handed out two drinks for the pair of women (ordered by Maggie) before commenting the cop "moving on"; confused, Alex inquires Sawyer if the waitress was a Roltikkon, to which Maggie confirms, along with the fact that she and Darla were formerly a couple, making Alex realize that she was just mistaken by the alien as Maggie's new flame. The next day, Alex, along with Maggie, attended President's Marsdin signing decree on the alien embassy act. During the ceremony Scorcher tried again to assassinate the President; they tried to stop her, but she ran away kidnapping Maggie an bringing her to a factory stock. Later Supergirl and Alex rescued the detective, who helped them fighting the alien terrorist. After a brief medical check-up at the D.E.O. Maggie thanked Alex for having saved her and then left, saying she had a date with a girl.
A few days later Maggie brought Alex to a crime scene, where they found the corpse of an alien and, according to the bruises on his fists, they concluded that before his death, he fought and was killed by another alien. Later, they went to their prime suspect's home, only to see him being kidnapped by few unidentified people in a van. In the evening, they infiltrated an underground National City fight club hosted by Roulette, in which the aliens are forced to fight to the death for the money. In the first battle, M'gann M'orzz fought the kidnapped alien Quill and is about to kill him, when Supergirl showed up, and Alex and Maggie shot into the air to disperse all those present.
Later at the D.E.O., Kara and Alex told J'onn they have seen M'gann in the underground fight club and, after both the martians are kidnapped, Alex informed Kara and goes to place where the fighting took place only to finds that there is nothing anymore. However, after Supergirl found out the new address in which Roulette was to host the battle, Alex and Maggie organized a police riot and arrested the woman who, anyway, managed to get released thank to her friends in high places. Before she get into her limousine, Alex told Roulette that her time will come and, after that, she invited Maggie to have a drink together, but the detective said she couldn't and left with her girlfriend. Seeing the couple walking away made Alex feel an odd jealousy.
Sometime later, Alex and Maggie were playing pool in the bar and the latter told Alex that she broke up with her girlfriend. Alex tried to cheer her up and, after they went to the site of a diamond robbery, Alex invited Maggie to go somewhere to hang out. Interpreting it as Alex asking her out, Maggie told her that she didn't know Alex was "into girls." A shocked Alex begins to deny it, but Maggie says that some gay women she knew had done the same thing, prompting her to leave. Beginning to realize her homosexuality for the first time in her life, Alex went to Kara's apartment and told her that she was confused about something, but seeing Kara upset, she immediately asked her what happened and the latter responds that Mon-El did not perceive the work seriously. Alex advised Kara to let Mon-El find what he is interested in. After that, Kara asked Alex if she was going to say something, but before she could speak, Lena came in and told Kara that she wanted to meet Supergirl.
That night, Alex found Maggie at the alien bar, she apologized for how she behaved insolently when considered that she was gay, but Alex said that she could not stop thinking about it and that in the fact could be the truth.
The next day, Maggie advised Alex to come out to her family and promised that immediately after that, they'll go to have a drink together. Later at the D.E.O. she and Winn showed J'onn a video of the Thorul Arctic Research Station in Norway, in which one of the scientists asks for help, Alex and J'onn go there only to find all the scientists were dead except for Rudy Jones, whom they brought back to National City.
The following morning, Alex asked Kara to talk in private, and they went out into the street. There Alex admitted to Kara that she had developed feelings for Maggie and that she is gay. Despite at first being shaken, later in her apartment, Kara told Alex that she understands how it feels to keep part of yourself locked away, and confirmed her support for Alex and her feelings towards Maggie. In the evening, Alex comes to the bar came into the bar asking M'gann for help as J'onn need a blood transfusion following his clash with Parasite.
The next night, Alex came back to the bar telling Maggie that she has come out to Kara, then kissed her. However, after the kiss, Maggie said to Alex that she wants Alex to experience being with a wowan for herself, and does not want to have a relationship with someone who has just come out, as that those relationships never really have good endings. After these words, Alex exited the bar with a disappointed face; feeling heartbroken and humiliated, and she went back to her apartment, where she was visited by Kara, who hugged her and began to comfort her.
Relationship with Maggie
A few days later Alex, Kara, Winn and James sat in the alien bar, discussing the new vigilante, when Maggie came in and asked Alex how she was doing, the latter pretended not to be offended by what happened during their last encounter and said that she was fine. The next day, Alex discovered from Winn that James is the Guardian and agreed not to tell Kara, then she approached Maggie, who had gained a warrant for the arrest of the Guardian, and asked her to stop the hunt for the vigilante, telling her that they are not looking for him, without revealing any further details. Maggie agreed as they're friends, but Alex told her that they are not because she was hurt that Maggie does not want to be with her. Later Alex returned to the D.E.O. and asked J'onn if there are any news from Kara, he said to wait before starting to alarm, then, suddenly J'onn aimed a gun to one of the agents because he sees him as a White Martian in a vivid hallucination, after Alex stops him, he asked her to do some medical tests on him, from which it results in his blood cells changing. After Kara fled from Cadmus and returned to the D.E.O., she told Alex that she saw her father and that he helped them escape so, along with several agents, Alex went to the secret base of Cadmus finding it completely empty. Later that night, at the celebration party for Kara and Mon-El's return in Kara's apartment, Maggie told Alex that she cherishes their friendship and hopes that they will be able to become friends, because she did not want to imagine her life without her. Alex agreed to meet her and play pool. Back at the apartment, Alex realized that Kara had overheard them, so she said that she and Maggie have chose to remain friends. Then Kara promised her that they will find Jeremiah.
During the Thanksgiving dinner at Kara's apartment, Alex tried to come out to her mother but was stopped by the opening of a breach.
After Mon-El is infected by the Medusa virus, while working to find a cure, Eliza asked Alex what she wanted to tell her, and she finally found the courage to come out to her mother, saying that she was afraid to disappoint her, to which Eliza replied she could never be and embraced her.Alex and Eliza, found that to spread the virus on National City Cadmus needs a substance produced by L-Corp, so Alex calls Maggie and asks her to send all their available troops to the company headquarters. However, there Cyborg Superman hurt Maggie whit his cybernetic laser eyes, and the woman is delivered to the D.E.O., where Alex checked her wound, then informed her that she had speak with her mother, and thanked her for having opened her eyes.
The next evening, Maggie visited Alex at her home, confessing that she had feelings for her, and the two shared a kiss, thus beginning their relationship.
Alex began to spend more time with Maggie as they explored their new relationship. When Kara had a lead on a missing person named Izzy, Kara insisted that she didn't need her help and that she could handle it on her own. However, she had gone missing and Alex tracked her by her last location and found that she had been taken to the planet Maaldoria where she wouldn't have her powers. Alex then became hysterical and blamed herself as she was distracted by her new relationship and didn't protect her sister. When Maggie arrived, Alex told her that she couldn't see her as Supergirl had gone missing and that it was her fault. Maggie was confused by how she was acting but Alex told her that she had to focus on getting Supergirl back and Maggie couldn't help her.
When Winn helped activate the portal to Maaldoria, Alex led a strike team to the fortress and arrived just in time to find that Kara and Mon-El were leading the other captured humans to safety. They headed back for the portal but an attack ship was heading for them and Izzy was grabbed by a Maaldorian. Alex then threw a yellow sunblast grenade which gave Kara her powers back and she used them to destroy the ship and save Izzy. They then all returned back to Earth. Later, Maggie visited Alex and told her that she was aware that her sister Kara was Supergirl as Kara was the only one that Alex could worry about as much as she did. Maggie also told Alex that she wasn't going anywhere and that she deserved to be happy.
After M'gann suffered from a telekinetic attack from the White Martians that left her in a catatonic state, Alex took care of her and informed J'onn that she was slowly dying. Although J'onn was hesitant about helping her because of his old hatred for her kind, however, after Alex talked to him he decided to save her life through the Martian Bond. Meanwhile she and Maggie helped Supergirl in her investigations to track down Livewire, strengthening both their professional and personal relationship. 
When Valentine's Day arrives, Alex learns that Maggie dislikes the holiday but is unsure why.
Return and betrayal
During a mission Kara rescued Jeremiah Danvers and he was reunited with his family, happy to be reunited Alex introduced her father to Maggie revealing her sexuality. Jeremiah accepted, but when Mon-El was suspicious of Jeremiah, it caused tension between Kara and Alex. It turned out though that Mon-El's suspicions was right as Jeremiah's rescue was part of Cadmus's plan as he was working with them. He stole the list of all known aliens, Alex, Kara and Mon-El confronted them, but Jeremiah escaped when Alex couldn't shoot him. J'onn decided to test Alex and transformed into Jeremiah, and asked for help. When Alex decided to help him, J'onn transformed back and had Alex suspended. Alex though refused this as she and Maggie tracked down a member of Cadmus about to kidnap an Alien. Alex and Maggie parted ways with Alex confronting her father and Lillian Luthor.
Prior to entering the base, Alex had rigged explosives around the area and had Jeremiah make a choice, her and the aliens or Cadmus, he chose to side with his daughter and the father-daughter duo worked together, but Jeremiah was knocked out and taken. Alex decided to stop a ship that was planned to leave Earth with all the aliens, in which Kara arrived and it was through Alex that Kara was able to stop the ship from leaving Earth.
Despite losing their father again, Kara and Alex's relationship was still strong, but Alex found that Maggie and Kara had trouble due to Kara's inability to wait. Maggie made a point in which Kara's actions in charging in and stopping robbers, have caused criminals to use the Supergirl defense in which her heavy handed tactics causes criminals to escape justice. When Alex tried to make peace between the two, she was kidnapped by Rick Malverne and was imprisoned. Throughout her time in the prison she told Kara and Maggie not to give in, and when she was almost killed, Alex was able to keep herself alive long enough to be rescued. Before Rick's mind was erased by J'onn, she punched him and told J'onn to make sure he remembered that.
When Queen Rhea of Daxam, made her plans to take over Earth, J'onn attempted to stop her, but she put him in a never ending nightmare, leaving Alex in charge of the D.E.O., in which she worked with Kara and Maggie to stop Rhea. When Lillian Luthor offers assistance, Alex and everyone else defiantly refuse due to fighting with her and C.A.D.M.U.S. for months but eventually agrees after Kara calls for her. When the President ordered Alex to fire a cannon at the Daxamite mother-ship, Alex was forced to make the tough call and was hesitant to fire the cannon when it was ready due to Kara being inside it. Unfortunately a mind controlled Superman destroyed it.
Alex and Maggie witnessed the battle between Superman and Kara in which the latter won. Alex took both of them to the Fortress of Solitude. After the final battle with the Daxamites, Alex tried to console Kara who was forced to send Mon-El away due to poisoning the atmosphere with lead to send the Daxamites running. Kara gave Alex some advice, which caused Alex to propose to Maggie who agreed.
Alex and Maggie's relationship grew stronger, with their wedding getting closer. Alex convinces Maggie to confront her past and led her to finally confronting her estranged father, but during that time, Alex discovered that Maggie didn't want kids, something that Alex has always wanted. Alex attempted to continue the relationship, but upon seeing the relationship between Samantha and Ruby Arias, she confessed to Kara, her desire to have children. Maggie, soon realized what was happening and told Alex, that she has to say it, in which Alex ended the relationship with Maggie. The two spent one more night together and the pair parted ways amicably, with Maggie telling Alex that she was going to be a great mom. The heartbreak that Alex suffered caused Kara to take her back to Midvale, in which the two ended up having an argument. The next day, the pair made up, and returned to National City, in which they found a ship which contained Mon-El.
Crisis on Earth-X
After having dealt with a Dominator, Alex and Kara talked about Mon-El in which Alex discovered a wedding invitation to Barry Allen and Iris West's wedding, though hesitant at first, Kara decided to go with Alex. Alex went to the rehearsal dinner, in which she started drinking and was soon joined by Sara Lance. Alex mentioned to Sara her sexuality and how she had to cancel her wedding, and the two continued to drink before making out outside Jitters. The two ended up at a hotel room in which the pair had sex, three times. Alex wakes up to discover Sara next to her and sneaks out. Alex arrived to the wedding where she and Kara talked until Sara arrived who asked if Alex was okay after falling out of bed, thus revealing their interaction to Kara. Kara told Alex that it was okay and mentioned how Sara was an assassin, Alex calls her a "sassy assassin". Alex and Kara entered the church and watched the wedding, but before the ceremony could continue, the priest was killed by Overgirl and the invading Nazi forces of Earth-X. Alex and Sara teamed up and took down many Nazi's as well as knocking out Prometheus.
Everybody returned to S.T.A.R. Labs in which they discovered that the Nazi's were from Earth-X. Alex runs into Sara and was nervous, though Sara didn't think too much of it. Alex then speaks with Kara and admitted that she doesn't know what to feel due to her sleeping with Sara and wondered if she made the right choice when it came to Maggie. Kara tries to console her but Alex believed that she made a mistake when it came to sleeping with Sara and breaking up with Maggie. When the team had discovered Overgirl's location, Alex and Sara teamed up again in which Sara asked if that was okay, Alex agreed. Alex battled along with the others and seemed to be winning until the arrival of Metallo who quickly took down Supergirl and Firestorm with ease, and Alex and the others were knocked out. Once they awoke, they were imprisoned and discovered that Overgirl was dying and that they planned to cut out Kara's heart and put it into Overgirl's. Metallo then knocked them all out again in which they were all taken to Earth-X except Kara.
After awaking on Earth-X, Alex and the group met Ray Terrill who revealed he was in prison because he loved the wrong person, this worried both Alex and Sara due to their sexuality. Suddenly they met the Earth-X version of Sara's father, Quentin Lance who planned to have them executed along with Ray. When they tried to escape they were shocked by the collars they were wearing and were almost executed until the arrival of Leo Snart. Leo freed them and helped them escape when he freed Ray which allowed him to use his powers. They escaped to the Freedom Fighters, who were led by the Earth-X version of Winn Schott, and he refused to allow them to go to the breach as he planned to have it destroyed. Alex tried to convince him due to knowing his Earth Thirty-Eight counterpart, but he still refused. Alex attempted to find a gun so that she could try to rescue Kara, but Sara stopped her by mentioning that she is part of her team now. Sara learned about Maggie and talked to Alex about her own Maggie, Nyssa. Sara then told Alex that she should follow her instincts and that her reasons behind the break-up were valid. Eventually Winn was convinced by Ray and Leo to attempt to get to the portal, in which Alex and Sara teamed up against the Nazi's. They succeed in taking the site, but during the conflict Martin Stein got injured.
Alex and the rest of the team along with Ray and Leo arrive back on Earth One, where with the help of the Legends, Team Flash and Team Arrow were able to rescue Kara and escape to the Waverider. Alex was reunited with Kara, in which Kara joked about how their plan to come to Earth One went up in smokes. They soon discovered that Martin Stein dies from his injuries. In the final battle with the Nazi's, Alex and Sara teamed up against the Nazi's and won after the deaths of Black Arrow and Overgirl. Alex attended the funeral of Martin Stein along with everyone else. Alex and Sara had one last conversation in which Alex agreed with Sara that she should follow her instincts, they hugged before parting ways. Alex and Kara said goodbye to Barry, Iris, Oliver and Felicity and returned to Earth Thirty-Eight.
The rise of Reign
After returning home, Alex along with Kara, Winn and J'onn listened to Mon-El and Imra's interpretation of their future, Imra revealed to them that they are part of a group called The Legion and that Mon-El helped create them through what he learned from Supergirl. Alex went to Kara's Christmas party, where she bonded with Ruby Arias through tales of her adventures with Supergirl, who Ruby idolizes. Later when an unknown Kryptonian arrives in National City leaving marks all over the city, Alex finds out along with everyone else that the Kryptonian is said to be the Krypton equivalent of the devil, Reign. When Reign finally makes her presence known and is called out by Kara, Alex tells Kara that she needs to embrace her Kryptonian side. Kara did, but was brutally beaten to unconsciousness. Alex arrived at the scene and took Kara back to the D.E.O. where she attempted to keep Kara alive after her brutal fight with Reign.
Alex is a courageous and independent person, who faces danger head on. She is caring, confident, and headstrong, with the same passion for bio-engineering like her parents. Alex had dedicated her life to protecting her sister, Kara, and rarely found time for herself since teenhood.
Despite her good traits, sometimes Alex can be impulsive and prone to make difficult decisions crossing the line between right and wrong (some might even classify her as morally grey); such as when she stabbed Astra in the back, or when she assaulted a Cadmus facility on her own by placing mines in the structure to blackmail Lillian Luthor, even if on those occasions it was to save first J'onn J'onzz's and then her father's life.
However, she has a great sense of justice, since when J'onn took the blame for Astra's death, as he did want not Alex to lose her relationship with her adopted sister, knowing it was wrong, she eventually confessed to Kara her role in Astra's death despite her fear to lose her.
After much soul searching and exploration, Alex finds the courage to come out as a lesbian to herself, then to her ex-girlfriend Maggie Sawyer, then Kara, her mother Eliza, her friends and her father Jeremiah. Alex's interactions with Maggie show a more flustered, awkward and almost goofy side of her personality, similar to that of Kara.
Above all, Alex is a strong woman. She fights for what she believes in and has a difficult time giving up. When she was kidnapped by her childhood friend, Rick Malverne, she never stopped trying to escape and was able to use her D.E.O. training to help her survive. She has been referenced as being a "badass" by many people.
After losing Maggie, Alex became devastated unable to cope with it and started drinking heavily. She also has a liking to leather jackets.
- Expert scientist: Alex displayed an aptitude towards science since her early childhood, as demonstrated by her interest in science fairs as a child. She was pursuing an MD/PhD at an accelerated speed  and finished the PhD portion by the time J'onn recruited her at the age of 24. Because of her PhD in bioengineering, she is also an expert in alien physiology and has used this expertise in multiple D.E.O. operations, such in the operation to capture the Hellgrammite who was raiding multiple chemical plants, when she figured out that the Hellgrammite has chlorine-based DNA and thus was attacking the plants to gather their stockpiles of DDT for use as food, rather than to gather chemical components to create WMDs. She is also a neuroscientist and a xenobiologist.
- Genius-level intellect/Expert tactician/Leader: Alex has sharp intellect, is an expert tactician and an extraordinary leader, capable of managing and organizing a handful of D.E.O. agents by herself. She is also the second-in-command of the D.E.O. and was the acting director of the organization when J'onn was captured by Non and Astra  and when J'onn was incapacitated during the Daxamite invasion.
- Peak of human physical condition: After a full year of training with the D.E.O., Alex is in top physical condition with heightened reflexes, strength and durability. She engages regularly in intense exercises to maintain her conditioning.
- Expert medic: Alex has performed medical procedures on humans, such as patching James Olsen up after he was knocked out by a super soldier with Livewire's abilities , and aliens, such as examining a comatose M'gann after she suffered a psychic attack and figuring out that a Martian mind meld with J'onn would be the only way to save her.
- Expert hand-to-hand combatant/Martial artist: As an agent of the D.E.O., Alex is an expert in unarmed combat and martial arts. As required by the D.E.O., Alex spent an entire year in training before being let out into the field, which included spending twelve hours a day for five months in the D.E.O.'s training room. She has proved to be capable of defeating multiple alien enemies at once with ease.Together with Sara Lance, she could defeat Tommy Merlyn.
- Expert knife wielder: Alex is capable of fighting with knives as seen during the Earth-X invasion.
- Expert interrogator/Torturer: Due to her time with the D.E.O., Alex is an effective interrogator and torturer. She once claimed to know six ways to torture someone with just an index finger. Her knowledge of interrogation techniques is so advanced that, when she was interrogated with the polygraph, Alex managed to fake the results.
- Indomitable will/High pain tolerance: Alex has shown that she is capable of tolerating a high amount of pain. When captured by Rick Malverne, she snapped her credit card in half and used its broken edge to cut deeply into her skin on her shoulder to remove her subdermal tracking chip with barely any reaction.
- Expert markswoman/Firearms: Due to her D.E.O. training, Alex is an expert with firearms, as shown when she was able to shoot at the Hellgrammite while in a moving vehicle.
- Expert swordswoman: Alex proved able to fend off various Kryptonians with a sword of Green Kryptonite.
- Expert driver/Pilot: Alex is an extremely skilled pilot, being able to drive both common vehicles and spaceships.
- Skilled stick fighter: When the bar got attacked, Alex used a pool stick to defend herself and her friends.
- Weapons proficiency: She is certified in over 30 government weapons. 
- D.E.O. tactical suit: While working on the field Alex wears a special protective suit made in an unknown black material with some stealth capabilities.
- Kryptonite-powered exosuit: Alex used a special cybernetic exosuit powered via Kryptonite, which she got from Non while under Myriad's mind control, to allow her to fight superhumanly stronger opponents such as Kara Danvers or Metallo by physically enhancing her. Also, the suit's forearm was fitted with a Kryptonite-powered energy gun and it could generate green, concussive shockwaves to physically repel and incapacitate opponents, especially Kryptonians.
- Maaldorian laser pistol: During a rescue mission on Maaldoria, Alex acquired an alien pistol from a fallen alien. The pistol itself is shown to be very powerful as it sends any target it hits over a distance and it has even proven strong enough to take down a White Martian, albeit weakened from J'onn and M'gann.
DC's Legends of Tomorrow
- "Invasion!" (mentioned)
- "Duet" (mentioned)
Adventures of Supergirl
TV Guide Comic-Con edition
- Alex Danvers' caller name on Maxwell Lord's phone is Mata Hari.
- Alex likes pizza and enjoys it more than most foods.
- She had the chicken pox when she was in High School.
- She wants to be a mom and have kids one day.
- Alex is one of only two Supergirl characters that appeared on all four main series to Arrowverse, (including Arrow, The Flash and DC's Legends of Tomorrow), the other being Kara Danvers.
- Alex has appeared in every episode of Supergirl, except "Worlds Finest".
- Alex becomes a new love interest of Sara Lance during the crossover "Crisis on Earth X".
Behind the scenes
- Alex Danvers is the only main character of the TV Show Supergirl who so far doesn't originate from the DC comics, being created exclusively for the TV series.
- In the DC comics, the Danvers did have a biological child, however instead of a girl named Alex, it was a boy named Jan.