- For his Earth One counterpart, see Tommy Merlyn.
- For the Earth One version of Prometheus, see Adrian Chase.
- "Your naïveté would be charming, if your weakness wasn't so pathetic. Is this how it is on your planet? Everybody's swayed by sentiment? Is everyone here really so weak!? The Reich will change that; the weak will be eliminated, your entire world will be enslaved, but you...you won't be around to witness it. He is going to feel your skull crack under the weight of his boot. Everyone you care about, everyone you love...they are going to die badly...in ways that would give even monsters nightmares. I really wish that I could live to see it."
- —Tommy to Oliver Queen, right before his suicide.[src]
Thomas "Tommy" Merlyn was a member of the Nazi military wing of Schutzstaffel in the New Reich, where he operated under the codename Prometheus. He was captured and held captive in S.T.A.R. Labs before killing himself via a cyanide pill.
Tommy was born to the Reich by unknown parents. He mentions not having a normal childhood. He, at some point, became friends with Oliver.
He journeyed to Earth One, along with Oliver, Kara and a squadron of Nazi soldiers, to attack the heroes that had gathered together for the wedding of Barry Allen and Iris West. He went on to engage both Alex Danvers and Sara Lance in combat but the two of them managed to overpower and beat him. He was then taken to S.T.A.R. Labs at gunpoint by Sara and Jefferson Jackson where he was locked up in one of their cells of the pipeline but hadn't spoken a word to any of them.
He soon removed his mask and everyone, especially Oliver Queen, was surprised to see that he was the doppelganger of Tommy Merlyn, who had died over four years previously. Oliver asked for his friends to give them some time alone. Tommy informed Oliver that he was from Earth-X and heard that the Tommy of this world was already dead and told him that he would actually prefer that. He told him that on his Earth, he didn't have a choice but to be put into military training for the Reich as a child because they didn't have elementary schools and summer camps like they did here. Oliver tried to convince him that he had a choice now and asked for help in trying to find out what the Fuhrer wanted. Tommy told Oliver that there was someone like him on his Earth and he would die for him. Oliver said that he would've died for his Tommy too but he had beat him to it. Tommy then revealed that his sob story was all a facade and that he actually enjoyed dominating over people and killing. He called out Oliver's sentiment as weak and asked him if all the people in this world were this weak as well. He told Oliver that the Reich would come and destroy the weak and then enslave the rest, but Oliver wouldn't live to see any of it as the Fuhrer would kill him. Tommy then told him that he wished he could live to see that himself. He then pulled out his tooth where there was a hidden cache of cyanide. Oliver moved to stop him but Tommy swallowed it and died a moment later.
His suit's bio sensor sent out a signal to Earth-X Oliver, notifying him of Tommy's demise. Oliver took a moment to mourn for him and told Kara that he had died for her and vowed they would make his death worth it.
Initially, it seemed that Tommy was a more sympathetic villain than his peers Oliver, Kara, and Thawne, claiming that he was indoctrinated into the Reich from birth and thus never had a true childhood, also noting that perhaps dying as his Earth One counterpart had would be preferable to an empty and miserable existence as a Nazi enforcer.
However, this show of being insecure, remorseful, and repentant was, in fact, nothing more than a facade done for the purposes of exposing Earth One Oliver Queen's gullibility in trying to reach out to an alternate version of his dead friend. His true nature revealed, Tommy mocked Oliver's high morals and idealism and sentiment, considering him and his friends to be "weak" and deserving of being crushed, also sadistically taunting Oliver with the promise that the Fuhrer would kill them slowly and horribly and make Oliver watch, and lamented how he, Tommy would not live to see it. In short, Tommy was ultimately shown to be every bit the sadistic Nazi henchman that his fellows Black Arrow, Overgirl, and Eobard Thawne were, and a man who reveled in and rejoiced in the cruelties of the Nazis.
- Peak of human physical condition: Unlike his Earth One counterpart, Tommy was trained from his youth in the Reich military to be in peak physical condition and has great athletic prowess.
- Master hand-to-hand combatant/Martial artist: Tommy was highly skilled in hand-to-hand combat, allowing him to fight against the likes of Sara Lance and Alex Danvers for a time before getting defeated.
- Master swordsman: Tommy was trained in the art of swordsmanship and managed to fight off Sara Lance and Alex Danvers with two swords.
- Prometheus suit: Tommy wore a protective suit while operating under his alias Prometheus.
- Chokuto: Like Adrian Chase, Tommy is shown wielding a chokuto he keeps on the back right next to his quiver.
- Quiver: Tommy is also shown having a quiver on his back, though he doesn't use the arrows stored in them or use a bow.
- Shurikens: Also similar to Adrian Chase, Tommy keeps at least six shurikens strapped to his abdomen, although he is never seen using them.
- "Crisis on Earth-X, Part 1" (as Prometheus)
Crisis on Earth-X
Behind the scenes
- This version of Tommy Merlyn, being a black-clad archer villian could be inspired by Tommy Merlyn of the Prime Earth variant in the DC comics continuity. Interestingly enough, he was originally inspired by Earth One Tommy Merlyn from Arrow.
- The Earth-X version of Prometheus being Tommy Merlyn could be a reference to the fact that during season 5, before Prometheus' true identity was revealed, there was a popular theory that Prometheus was actually a resurrected Tommy in disguise.
- According to Stephen Amell, Colin Donnell, still being very busy at the time of the filming of Crisis on Earth-X, managed to get enough free time one night to get on a flight to Canada, perform his scene at the S.T.A.R. Labs pipeline prison, and fly back to his rigorous working on Chicago M.D. (which had been referenced in the previous crossover as Tommy being a doctor in Chicago in the Dominators' illusionary world).
- Like the Earth One Prometheus, Tommy taunted Oliver about the prospect of his friends dying before killing himself.