Superman: Doomsday

Lex is featured in the direct-to-video animated movie Superman: Doomsday. Lex's character design is similar to those seen in Superman: The Animated Series, albeit with a much slimmer profile and a white suit, and is voiced by James Marsters; Marsters also portrayed villain Milton Fine (Brainiac) in the fifth and seventh season of Smallville. Here he's shown as highly intelligent (able to cure every known case of Muscular Dystrophy), but extremely amoral (has his scientists find ways to draw out such cures to make a higher profit).

In the film, Lex is indirectly responsible for the release of the creature Doomsday. Upon discovering that the latent radiation from the Earth's core can be harnessed for energy purposes, LexCorp has been illegally drilling into the earth. When Lex's miners stumble upon Doomsday's alien spacecraft while digging, they accidentally damage it and awaken Doomsaday from his long slumber. After the creature slaughters the mining team, Lex orders his personal assistant, Mercy Graves, to cover up his involvement; when all other loose ends have been tied up, Lex kills her to prevent any chance of a leak.

Following Superman and Doomsday's epic battle, Superman lies dead, and Lex is free of all culpability. Rather than be pleased, Lex is incensed that the evidence crediting him to Superman's death has been destroyed. Lex then robs Superman's body from his grave with the intention of creating genetic clones of him. The cloned Superman is more violent than the original, killing crooks, threatening civilians, and generally behaving like a public menace, even causing the death of Toyman by dropping him from a large height during the criminal's arrest because Toyman killed a little girl. Meanwhile, the real Superman's corpse disappears from LexCorp during an electrical blackout (it is later revealed that Superman's robot servant at the Fortress of Solitude rescued him after seeing minor pulse fluctuations through separate days, realizing Superman wasn't dead).

Lex is visited in his office by Lois Lane, who says she feels distant from her relationship with Superman (not knowing that he is a clone). Lex tries to seduce her and they kiss, but Lois uses a tranquilizer on Lex and knocks him unconscious; Lois believes he is the one behind Superman's strange behavior. Lois and Jimmy Olsen uncover Lex's cloning project, but Lex reappears and tries to shoot them. Fortunately, the cloned Superman has freed himself from Lex's control and steps in to rescue Lois and Jimmy. Lex escapes to a room with red sun beams, similar to Krypton's Red Sun, which will neutalize Superman's powers; he also dons kryptonite gloves, with the intention of beating the insolent clone to death. Instead, the clone traps Lex in the vault, rips its foundation out of the building, and throws the vault across Metropolis. At the end of movie, it is revealed that Lex survived, but with severe injuries. He is aware of the real Superman's survival at this point, and his final line in the movie is: "If it has been proven that gods can die, it is also proven they may return from the dead. It would seem you can't be destroyed after all, Superman. It would seem."