- "I don't trust anyone's word, Mr. Diaz. I put my faith in data, information. Ones and zeroes never lie."
- —Cayden James to Ricardo Diaz[src]
Cayden James (died February 8, 2018) was the father of Owen Post, and the founder and leader of Helix, an organization uniting masterful hacktivists. Although no official case was formed against him, he was denoted as a "person of interest" by A.R.G.U.S. and illegally imprisoned in a black site facility. James's Helix allies, led by Alena, eventually rescued him with help from Felicity Smoak. His time in custody caused him to go insane, and he developed a plan to wipe out the world's internet, recruiting Black Siren to his side and clashing with Team Arrow, as well as his former allies Alena and Felicity.
Believing Oliver Queen was responsible for the death of his son, the master hacker committed a series of attacks throughout Star City, wanting to avenge his son's death and formed his own cabal to do so. It was later proven to him that Oliver was not responsible for Owen's death, and James was subsequently taken into custody. Shortly thereafter, he was killed by the true mastermind behind his son's death; James's former associate Ricardo Diaz.
Founding Helix and A.R.G.U.S. imprisonment
At some point, Cayden James founded Helix, an organization uniting hackers that pursued political activism. Considered by A.R.G.U.S. to be 20 times more dangerous than Snowden as a security risk, James was captured by the organization when he was supposedly trying to hack an A.R.G.U.S. transponder. Although his crime was not proven in court, Amanda Waller illegally gave the order to keep him imprisoned as a "person of interest". James was moved to a black site prison, which was eventually located by his Helix allies in 2017.
The Helix rescue team led by Alena and Felicity Smoak ventured into the facility, opposed by A.R.G.U.S. security force and Team Arrow. They successfully extracted James and moved him to an undisclosed location. Back in the command of his organization, the Helix leader decided to cut off ties with Felicity, considering her ties to Team Arrow a liability, but worked with the code to figure out a program she was looking for that would allow locating Prometheus's location. Leaving a flash drive for Felicity's use, Helix evacuated from their old base to a new location.
While in Corto Maltese, James received a package which contained a USB which revealed that his son was killed by the Green Arrow, this caused him to make plans to have vengeance on the Green Arrow who he soon discovered was Oliver Queen. This change of attitude made Alena think that it was the aftereffects of prison not knowing it was really due to the death of his son. He developed a plan to destroy the world's internet as a whole, even worse than the Calculator's plan. Seeking out allies for his scheme, he observed the battle on Lian Yu and saved the life of Laurel Lance/Black Siren, adding her group's strength to the power of Helix.
When Alena disagreed with James's plans, he attacked her, making the young hacktivist escape Helix while pinging his phone in Corto Maltese. Alena seeks out for Felicity's help, and the two tried to contact Amnesiac for the ghost drive. They eventually came to the old Helix building intending to prevent Cayden's plans but were caught by his team, which included Black Siren. James explained his disappointment in Alena being duped by his Corto Maltese phone and tried to execute the two women, but was stopped by Team Arrow.
Cayden and Black Siren's group went on their path to the International Domain Name Directory vault, slaying all the guards. They were pursued by Team Arrow, with Oliver Queen taking on the role of Overwatch. Thanks to her personal presence on the field, Felicity managed to remove James's internet-threatening virus, but only through taking down the facility's firewall processors, with them exponentially overclocking and the cooling system disabled. However, it was never James's plan to take down the internet, but rather to get Felicity to take down the firewall, leaving her "digital fingerprints". Once Felicity had taken down the firewall, James was able to upload a critical piece of code to Arclight. As such, he would be able to frame Felicity for the results of his true plan.
With Black Siren's help, James created a new plan, involving a terrorist attack on Billy Joel's concert, masking his men as police officers. As Green Arrow arrived at the stadium, he was confronted by James, who explained that the bomb was a hoax and he merely wanted to see Oliver and talk with him tête-à-tête, saying that Oliver was responsible for the death of his son, and all James truly seeks is revenge. He enacted a part of his revenge by releasing footage of Team Arrow members beating up his goons masked as police officers, swaying public opinion against vigilantes, who were seen "attacking SCPD officers".
James had Black Siren kidnap Quentin Lance and blackmailed Oliver Queen to steal an item from A.R.G.U.S. James discovered that Oliver had sabotaged the device but convinced Oliver he had no idea and met him at a digital black point so Felicity couldn't observe them. James confronted Oliver and mentioned he is a man of his word as he wouldn't tell Oliver that he would destroy the city if he wasn't. When Oliver demanded proof of life from Quentin, James agreed and proved that Quentin was still alive. When Oliver handed over the device, James refused it knowing it was sabotaged and ordered Black Siren to kill Quentin and have his men kill Oliver. Both plans failed though when Oliver and Black Canary fought off the attackers and Black Siren freed Quentin instead of killing him. Later on, James watched Team Arrow self-combust as it was revealed that when he sent Black Siren to attack the Arrowcave, she had set up a secret camera as well. Black Siren questioned if this is what he planned when he had her set the secret camera up, but he admitted that it was more then he was expecting. Soon other members of his secret Cabal arrived including Anatoly Knyazev, Vincent Sobel/Vigilante, and Ricardo Diaz/Dragon.
James along with Black Siren and Ricardo Diaz visited Jerry Bertinelli and threatened him to give up his access to the docks, they gave him 48 hours or he would send Black Siren to New York to have her pay a visit to his daughter. While at their base of operations, Black Siren complained how it would be easier to just kill Bertinelli and they would soon be attacked by Green Arrow, only for him to be surprised by the appearance of Cayden's Cabal. James allowed Green Arrow to escape much to the chagrin of Black Siren and Diaz. After over-hearing a conversation between Team Arrow, James sent his Cabal against Bertinelli, who was secretly working with the Green Arrow. James's Cabal was successful in subduing Green Arrow, in which James offered Bertinelli a choice to kill Green Arrow, and realizing his failure Bertinelli decides to kill Green Arrow, but he escapes. Despite giving James the docks, Cayden had Bertinelli killed but told his dead body that his daughter was safe.
Attacks on Star City
James initiated his plan and caused many accidents throughout Star City killing many people including Captain Frank Pike. James then visited Oliver Queen at City Hall and told him that unless he pays $10 million every night, there would be more incidents. When Oliver confronted him about this James revealed the events that led to his son's death stating that he was killed by a stray arrow from Oliver a year ago, unknown to James at that time Oliver was at Hub City recruiting Dinah Drake, meaning someone framed Oliver for the death of James's son. After Oliver released a public announcement revealing that the incidents were caused by Cayden James, James sent Sheck and Vigilante to attack one of the safe houses that Oliver had created to protect the people of Star City, unfortunately for James, this fails and leads to the death of Sheck. Despite this, as the day approaches James's deadline Oliver is forced to give in and pays the money.
He soon discovered that Vigilante was a spy aiming to take down the Cabal. After Vincent stole certain data, he was captured by James and Anatoly. James had both Ricardo Diaz and Anatoly torture Vincent to reveal that he is a traitor. Once Vigilante escapes with Dinah Drake, James and Black Siren ambush them ordering Siren to end Vigilante's life and even threatening her when she hesitated.
After Cayden James announces that he is about to detonate the bomb at midnight, Team Arrow finally gives video evidence with help from the Flash that Green Arrow didn't kill Owen but someone else did. He recognizes that one of his former Cabal members had doctored the video. He makes Team Arrow find his former allies and brings them to him with the threat of the bomb. The presence of William caused James to remember his own son causing him to be vulnerable allowing Green Arrow to subdue him. In prison, he advises Oliver to be a better father and asks him to visit his son's grave which he accepts.
Ricardo Diaz later appeared to the arrested Cayden James and told him that he'd used James to take over Star City saying that it's ripe for the taking and that James was too clueless to realized he was used by Diaz. He also stated James doesn't understand that things should be taken over and not destroyed while revealing he bribed the new police captain. He then murdered James telling him he was the one who had his son killed and calmly exited the building.
LegacyThe public believes that James was killed by an inmate doing his transfer to Iron Heights Prison, however, Felicity Smoak eventually discovered that he never actually made it to Iron Heights, as he was actually killed in the interrogation room by Ricardo Diaz and it was covered up by the police, after realizing there are several members of the Star City Police Department under Diaz's payroll; Felicity reports her discovery to Team Arrow and the Outsiders respectively, as Dinah Drake and Quentin Lance are working together to find out how many police officers are under Diaz's payroll, in order to remove the corruption from Star City Police Department and regain control of it.
In the end, Oliver turned himself over to the FBI in exchange for their help in taking down Diaz, his criminal empire began falling, his entire influence over Star City was destroyed and he was forced into hiding.
- "...with perfect knowledge, Man can control anything. Everything."
- —Cayden James[src]
According to Alena, Cayden James was once a good man who only took up hacktivism as a means of helping the down-trodden and people without voices who were abused by the rich and powerful similar to Oliver Queen’s motivation in his first year of vigilantism. His belief in the good of his mission was so great that he neglected time with his family, estranging his son and wife out of fear if they ever became involved in his line of work their lives would be at risk. Nevertheless, James loved his son, Owen Post, greatly and his death completely shattered the good man he once was turning him into a broken, vengeful person.
His imprisonment by A.R.G.U.S. made him utterly insane and self-righteous, physically harming his former friend, Alena for questioning his plans in contrast to the Cayden James who first met her as an equal on her first day at Helix. A similar situation happened when Black Siren falsely confessed to murdering his own and James slapped her in response. This shows that although James is intelligent and relies on strategy for his grand plans he at times finds brute force necessary despite being the messier and less preferable option. James possessed a calm, collected, yet also smug attitude, considering everyone a pawn in his plans. In spite of that, he has some fondness for his allies as he handsomely rewarded his cabal for assisting him in his plans and personally thanked them all for helping avenge his son. James does not tolerate treachery in any way, executing the Vigilante and Jerry Bertinelli for working against him with Team Arrow, the latter was also a father who promised he would not kill his daughter, showing he would have killed anyone to accomplish his goals regardless if he sympathized with them but unveiled a twisted sense of honor.
Abandoning his crusade as a hacktivist, James as a cyber-terrorist seemed to enjoy his status as a mastermind, repeatedly taunting his enemies for their inability to touch him or combat him in his own realm. In his prolonged campaign to make Oliver Queen suffer, James bankrupted Star City of its resources and murdered innocent people. However, ultimately, he was motivated by the passion for his dead son, Owen Post whom James considers a victim of Oliver Queen's activities as a vigilante. Since discovering Oliver did not kill Owen, James grief and insanity reached a magnitude that he was intensely suicidal willing to destroy all of Star City’s inhabitants and himself just so his son’s killer would be killed as well.
In his final moments, James made amends to Oliver, displaying guilt and remorse for his actions and even providing information to help redeem his actions with all he asked for in return was to visit his son’s grave a final time. James found solace in the man he hated for so long and wished that he would be a better father than he ever could, having previously witnessed Oliver’s own love for William Clayton that James felt for Owen.
- Computer specialist/Master computer hacker: James was a highly skilled computer hacker, so much that he was able to hack an A.R.G.U.S. transponder. His abilities made him a "person of interest" for A.R.G.U.S. and a security risk considered 20 times more dangerous than Snowden. As soon as he was freed from captivity, he managed to immediately figure out the code for the program that Felicity needed, something neither she nor Alena could figure out on their own. According to Alena, he was the best hacker on Earth One so far that no one has ever heard of him, hence making James one of the best computer hackers and one of the most intelligent individuals in the multiverse.
- Genius-level intellect/Master tactician/Leader: James not only created and ran Helix as a powerful organization but also inspired loyalty into hackers under his cause, so much that they staged a massively dangerous operation to rescue him from a heavily guarded government facility. During his attacks on Star City, James staged plans that would cause misdirection for Team Arrow such as pretending to blow up a stadium full of people when he really wanted to make the public witness vigilantes attacking his men under police uniforms.
- Prototype T-Sphere: James used the Prototype T-Sphere that Black Siren stole from the Arrowcave against Oliver Queen (under the guise of Green Arrow). 
Behind the scenes
- Cayden James is similar to past characters Michael Emerson has played such as Benjamin Linus from Lost,” Zep Hindle from “Saw, and Harold Finch from Person of Interest.
- He is similar to Harold Finch in that: they both address people by Mr/Ms, they do not enjoy killing, they both have genius level intellect, they were both noted to be a "Person of Interest" which Michael Emerson had a co-lead role in, they are both excellent hackers. They are both wealthy, except Harold Finch is the good guy who cares about people and Cayden James is a bad guy.
- He is similar to Benjamin Linus and Zep Hindle in that: they are both villainous.
- In We Fall, James introduces himself as Ben Gale, a combination of the name of his character in Lost (Ben Linus) and the name he had used at the beginning of that series (Henry Gale).
- Cayden James was initially the main antagonist in Season 6, but was eventually outranked by the true main antagonist.