Gods are selfish beings who fly around in little red capes and don't share their power with mankind.
~ Lex Luthor talking about Superman ,and how about he hates him
Kryptonite! You're asking yourself, How? [kicks Superman] Didn't your dad ever teach you to LOOK BEFORE YOU LEAP?! Crystals, they're amazing, aren't they? They inherit the traits of the minerals around them, kind of like a SON INHERITING THE TRAITS OF HIS FATHER!! You took away five years of my life. I'm just RETURNING THE FAVOR!
~ Lex beating up Superman after luring him onto a Kryptonite-filled landmass.
Lex Luthor is the main antagonist of Superman Returns. He is an evil criminal mastermind and genius sceintist who his scheme is to defeat and kill Superman, his longtime archenemy for taking away five years of his life and to weaponize kryptonite in order to take over the world and USA.
Lex Luthor tries to take over the world by destroying some of the earth and creating a huge land mass which everyone will have to pay a big amount to live there. He sneaks behind Superman's back to an arctic region that Superman often visits, and he finds out how to access the main computer that will tell him anything he wants to know about Krypton. After that, he finds and steals some Kryptonite so that he use it against Superman, knowing that it makes him weak and deprives him of his powers. Also some of the Kryptonite he stole he put in the substance that helps make land. By doing that he was able to make a land mass that Superman would be powerless on. So Lex was able to get in close and stab Superman in the side with a shard of Kryptonite. By doing that, he nearly killed Superman and became rich. Since his plan back fired, Superman survived and took away his island and his crew. Her assistant who has a conscience, took away the fortress of solitude crystals and drop them. So, Lex can't build another Kryptonian island that ruined his plans for good. Both of them escaped from the helicopter and landed on a deserted island.
Because of Spacey's Acadamy Award wining performance in Singer's film The Usual Suspects (1995), and friendship with the director, Spacey was the only actor considered for Lex Luthor. The writers specifically had Spacey in mind for the part when writing the script. Spacey's version of Luthor has the same comically exaggerated vanity and pompus arrogance of the earlier Gene Hackman version as well as the same strong interest in real estate, but Spacey's version is far less campy and more serious. Spacey later said that director Singer told him to play the character more as "darker and more bitter" compared to Hackman and not to use the earlier portrayal as an inspiration.
Coincidintally, both Kevin Spacey and Gene Hackman (who played Luthor in Superman and Superman II, to which Superman Returns is an alternate sequel) have also previously voiced the villains of from two separate but very similar animated movies released in 1998. Spacey voiced Hopper from Pixar's A Bug's Life, while Hackman voiced General Mandible from DreamWorks Antz.