Lex Luthor (Michael Rosenaum) is the son of Lionel Luthor (John Glover), founder and CEO of LuthorCorp. Lex is sent to Smallville by his father to run a fertilizer plant owned by LutherCorp, but is soon involved in a car accident by driving off a bridge. He is saved by Clark Kent (Tom Welling) and quickly strikes up a friendship with him, oblivious to the fact that Clark is not of this world. Despite the wealth and prestige Lex earns simply by being a Luthor, his relationship with his father is perpetually strained, with a level of distrust felt by both Luthors toward each other.
As a child, Lex was caught in a meteor shower, one which, unknown to Lex at the time, heralded the arrival of Clark to Earth. As the result of his ordeal, Lex lost his hair and was left bald ever since. Perhaps indicative of this event, Lex has a great deal of curiosity in the unknown, which leads to a great deal of his future trials and tribulations.
Over time, Lex Luthor is married three different times, each relationship proving more unfortunate than the last. His first wife, Desiree Atkins (Krista Allen), married him with the sole intention of stealing his money. His second wife, Dr. Helen Bryce (Emmanuelle Vaugier), attempted to murder him during their honeymoon. And his surprising third wife, Lana Lang (Kristin Kreuk), married him once he deceived her into believing she was pregnant with his child. Perhaps not so surprisingly, upon learning of his deception, Lana arranged her own false murder and attempted to frame Lex for it.
Lex is a man of very ambiguous intentions. His complexity puts him on the borderline of good and evil, aspects of which he demonstrates throughout his life. Highly intelligent and ambitious, Lex is driven by his own desires and would easily be a self-made man even without his family's inherent wealth. Being such a powerful figure in Smallville coupled with his insatiable curiosity, Lex is often at the heart of each strange occurrence that befalls the town. While often motivated by his curiosity, Lex also finds a great deal of interest in amassing power and control in these situations, a position that often creates distrust between him and his friends.
It is his friendship with Clark Kent that becomes the source of his strongest obsession, however, when Lex finds himself intent on discovering the secret of Clark's mysterious past. This becomes an unfortunate catalyst for Lex's gradual descent into evil, a seed already planted by his father's animosity towards him. Before his complete downfall, Lex proves to be a devoted friend to Clark and his good nature does appear on the surface time and again. Perhaps were it not for fate being seemingly turned against Lex or his own childhood scars, he could have been a powerful ally to Clark Kent.
Lex is killed in an explosion arranged by Oliver Queen (Justin Hartley) in revenge for the death of his parents when he was a child. Lex cloned his DNA before he died but the clones were affected by some type of disease and none appear to be completely viable.
"In my experience, there's no such thing as too much information."
"You see, I don't want to do good things; I want to do great things."