Louis Leery was the secondary antagonist in the Season Three premiere "Exile" of Smallville.
After Lex Luthor married Helen Bryce they boarded a plane to their honeymoon. Along the way, something went terribly wrong and Lex woke up to find the plane empty and crashed into the ocean. Lex managed to survive the crash and ended up on a deserted island where he spent over three months.
In the island, Lex met Louis Leery Jr who helped nurse him back to health after he contracted malaria. Louis was a free-spirited individual who seemed perfectly content to be stranded and torments Lex with the suggestion that either Lionel or Helen betrayed him. Lex responded by threatening Louis if he ever insulted Helen again.
He tells Lex he should let go of his old life and enjoy life on the island. Lex survived by eating insects on the island when he saw a plane fly overhead. He tries to send out a smoke signal but Louis would not help and the opportunity was missed. Louis repeats that Lex belongs on this island and he must accept his fate.
Lex would attempt several more escape attempts from the island but would be constantly ignored by Louis. Once Lex attempted to build a raft, and Louis refused to help, claiming that he was not going to let Lex commit suicide. Lex used the compass Jonathan gave him on his wedding day to forage for food when he came upon a skeleton. He saw a necklace floating in a puddle of water but when he pulls it out it was attached to a skeleton.
Louis appeared and reveals himself as a psychopath by admitting that the remains are of his father, whom he had to kill because only one of them could survive. He then tearfully admitted that he thought that they were kindred spirits, to which Lex responded that he was a psychopath.
Louis retorted "Well, there's one in all of us. I just let mine out." He then attacked Lex with a machete. Louis chased Lex through the jungle and they began to fight on the beach. Lex gets the upper hand and hacks Louis to death with a machete, but he is approached by a third figure, a crew on a boat that had come to rescue him.
Lex tried to explain that he had to kill him but is astonished to see that Louis had disappeared, the machete was really a stick, and that most of his experiences on the island were, in fact, a figment of his imagination.