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He is not a man! I was the Man of Tomorrow! Not him! NOT! HIM!
~ Lex angrily expressing his hatred of Superman to his sister Lena prior to his arrest.
Your friends have been lying to you from the start. Your boyfriend, Jimmy. Alex. J'onn. That little alien runt, Brainy. Even your own mother. They mocked you, humiliated you, betrayed you. Every... last... one. Denial's a very powerful thing, isn't it? It's been standing right in front of you all this time and you chose not to see it. Kara Danvers is... Supergirl. I'm about to die, but at least I lived without ever being a fool. You're left with no one and nothing.
~ Lex's last words to Lena before his death just as he reveals Supergirl's identity to her.
Alexander Joseph "Lex" Luthor is a supporting antagonist in the TV series Supergirl, being an unseen antagonist in Season 2, the main antagonist of Season 4 and a cameo antagonist in Season 5. He returns in the 2019-2020 Arrowverse crossover Crisis on Infinite Earths as an anti-hero.
He is the former CEO of Luthor Corp (later L-Corp) and the archenemy of Superman as well as the half-brother of Lena Luthor and the son of Lillian Luthor. He is obsessed with destroying Superman by any means necessary as well as removing all aliens on Earth to prove himself as the superior individual.
He is portrayed by Jon Cryer, who is best known for portraying Alan Harper on Two and a Half Men, and also played Lenny Luthor, Lex's nephew in Superman IV: The Quest for Peace and voiced Freakshow in Danny Phantom.
Equipment and Abilities
Enhanced Physiology (Formerly): The Harun-El serum he injected himself with has given Lex great superhuman physical prowess. He was able to physically block Supergirl's punch, lift the entire Daily Planet globe and smash it down on Supergirl. The Harun-El serum he injects himself with has even granted Lex the power to regenerate from his failing health and even cure his self-inflicted cancer. He lost these abilities when Lena injected him with an anti-serum.
Genius-Level Intelligence: Lex's primary asset is his astounding genius-level intellect, which even amongst the Luthor Family is unrivaled. Lex Luther has passed a genius-level intellect from a young age, making him a child prodigy during his youth.
Scientific Mastermind: An extraordinary scientist, Lex is a genius expert on multiple scientific fields such as bio-engineering and biology. He was capable of injecting himself with Green Kryptonite and understanding the Harun-El much faster than Lena did. His mastery of extraterrestrials, especially Kryptonians, is even acknowledged by the governments of the world, is perhaps the greatest expert in the world.
Master Engineer: Lex is a brilliant inventor with great specialization in multiple fields of engineering that Lena admits to surpass hers, being able to design many sophisticated devices such as an "earthquake machine" that triggered a fault line in California, a device to turn Earth's sunlight red, a warsuit to argument his physical attributes, and secret computer room inside his cell. He is also a master computer programmer, as he was able to turn his watch into a miniaturized computer with which he could seamlessly take over multiple complex devices.
Master Manipulator and Strategist: Lex was personally trained in playing chess by a chess grandmaster named Anatoly Karpov, which he mastered enough to transfer the knowledge of checkmate to even dimwitted prison inmates. An extremely skilled strategist and manipulator capable of devising extremely complex plans that are backed up further with long term plans and manipulating and deceiving others Lex was able to first deceive Superman for years of his true nature and then stalemate him in their war for an extremely prolonged time before ultimately getting outsmarted and imprisoned. Lex was eventually able to successfully escape his imprisonment.
Mentoring Capabilities: Lex is a capable teacher and has even spent his prison sentence, mentoring prison inmates to pass on some level of intelligence to them, particularly in playing chess. Lex even mentored red Daughter by sending her books and teaching her chess as well as honing her accent to speak English in a more Americanized accent.
Miscellaneous Abilities: In addition to his scientific and strategic abilities, Lex also possesses other remarkable intellectual skills. He is an exceptional businessman, with his success in maintaining Luthor Corp's standing as a multi-billionaire corporation being famous throughout the world, and was able to continue this up until his arrest while also engaging in war with Superman with no problems at all. While not known to have either an M.D or doctorate, Lex was a sufficiently knowledgeable and skilled medic to be able to correctly diagnose his condition and heal himself. Lex speaks a variety of languages, particularly English, Latin, Kaznian, Russian, and has even managed to master Kryptonese. Lex also has incredible artistic skills, which he used during his prison sentence to sculpt impressive images on the walls to pass the time due to boredom, with him even noting painting was a mere geometry to him.
Lexosuit Applications: Lex Luthor has built himself a technologically advanced exoskeleton which he uses during his crusade against Kryptonians and other extraterrestrials. While wearing the Lexosuit, Lex displays a strong mastery of its combat functions and weapons usage, when compared to other uses of his Lexosuit. The exoskeleton has the power to materialize and de-materialize on him upon his command. The Lexosuit greatly enhances his physical strength and resilience to the point where he can go toe-to-toe against solar-powered Kryptonians. The Lexosuit even possesses onboard technology which projects Kryptonite-based energy beams and can manifest energy shields.
Immense Resources: Even after his incarceration into a maximum-security prison, Lex has somehow maintained his dense network of commodities, assets, influence, information, and connections throughout the world. He was able to arrange for issuing assassination contracts and even manipulated the government to give his sister a position within the D.E.O.
"Will The Real Miss Tessmacher Please Stand Up?" (mentioned)
"Red Dawn" (television)
"The Quest for Peace"
"Event Horizon" (poster)
"Stranger Beside Me" (mentioned)
"Blurred Lines" (mentioned)
"Dangerous Liaisons" (mentioned)
"Confidence Women" (flashback)
"The Wrath of Rama Khan"
"Crisis on Infinite Earths: Part One" (flashback)
"Crisis on Infinite Earths: Part Two"
"Crisis on Infinite Earths: Part Three"
Luthor's previous friendship with Superman mirrors the same relationship his counterpart had with him in the Smallville series.
Interestingly, Lex would go on to try and kill the Smallville's version of Superman during the Crisis on Infinite Earths.
Long before he appeared in the series, he was repeatedly referenced and mentioned by many heroes and villains, and he was best remembered for his crimes of terrorism against both human and alien life as well as his rivalry with Superman.
Although he only appeared in four episodes, Lex ultimately outranked Ben Lockwood, the Children of Liberty, Red Daughter and President Phil Baker as the main antagonist when it was revealed that they were pawns in his plan the entire season.
Lex was also behind the formation of the Children Of Liberty and turning Ben Lockwood into Agent Liberty through Mercy Graves.
He also knows Kara Danvers is Supergirl, which he later uses to his advantage. During the season finale, he revealed this information to Lena just before his death, ultimately driving a wedge between the two best friends.
When betraying and destroying the Kaznian army during the Season 4 finale, Lex is singing "My Way" by Frank Sinatra, which also played during the flashback of his trial.