In Season 5's finale, Brainiac unleashed a deadly computer virus on the world while Zod, an evil Kryptonian responsible for the destruction of Krypton, took over Lex's body, imbuing Lex with special abilities much like Clark's.
When Lex confided in Lana Lang about his new powers, the two grew closer. Clark realised that the only way to stop Zod was to kill Lex with a crystalline dagger left by Jor-El, Clark's biological father.
He found he couldn't murder his former friend though so Clark impaled Brainiac with the dagger instead, inadvertently opening the portal to Zod.
The resulting explosion sent Clark to the Phantom Zone, leaving Lex/Zod to rule the world.
Lois Lane and Martha Kent were left unconscious on a LuthorCorp jet that was about to crash, while Lionel Luthor and Chloe Sullivan were trapped in a limousine surrounded by rioters.
In this sixth season, Clark must battle his way out of the Phantom Zone. Thrown into this Kryptonian jail created by Jor-El, he finds himself without powers and surrounded by revenge-seeking criminals sent away by his father.
Jor-El's former assistant, a young woman named Raya, comes to Clark's aid in the Phantom Zone and helps him escape. Unfortunately, others escape as well.
The guardians of Clark's secret identity were always his adoptive parents, Jonathan and Martha. However in Season 5 Jonathan died of a heart attack after discovering that Lionel also knows Clark's secret. Feeling responsible for his father's death, Clark has a difficult time adjusting to the loss.
Martha took over Jonathan's Senate seat and hired Lois to be her chief of staff. This season, Martha continues to adjust to life without Jonathan, but she is conflicted about her growing feelings for Lionel. Although Lionel has offered to help Clark, Martha is unsure of his motives.
In Season 5 Lana felt utterly betrayed by Clark and turned to Lex for comfort. Encouraged by Lex's seeming openness, she vowed to stand by him. This season, their relationship gets serious, widening the gap between Lana and Clark.
While Lex loves Lana, he is still driven by his ambitions and continues down the path of evil. And although he promised to always tell Lana the truth, he realizes that some things need to stay a secret in order to maintain his relationship with her.
Clark and Lex's friendship has completely dissolved, and the two have become enemies, forcing Clark to work harder to protect his secret. On top of the fact that Lex stole Lana from him, Clark sees the dangerous path Lex is taking and vows to stop him.
In Season 6, best friends turn into bitter enemies representing the very forces of good and evil.
Additionally, there's a new billionaire in town with the arrival of DC Comics character Oliver Queen, aka Green Arrow. Although he has no superpowers, Oliver is a gifted archer who qualified for the U.S. Olympic team but chose to put his skills to work as the "emerald archer" instead, stealing ill-gotten gains from the rich and giving them to the poor.
Oliver comes from Star City to Metropolis to aid in the recovery from Brainiac's deadly virus. While in town, he meets and is charmed by Lois, igniting suspicion and a little jealousy in Clark.
When Oliver discovers Clark's abilities, he asks Clark to join him in a new project - forming a league of superheroes.
Meanwhile, Chloe is pleasantly surprised when her former fling, aspiring photographer Jimmy Olsen joins the staff of The Daily Planet, and the two rekindle their relationship.
Smallville was developed for television by Alfred Gough and Miles Millar, based on the DC Comics characters. Kelly Souders and Brian Peterson, Todd Slavkin and Darren Swimmer serve as executive producers, along with James Marshall, Mike Tollin, Brian Robbins and Joe Davola.
The series is produced by Tollin/Robbins Productions and Warner Bros. Television. Superman was created by Jerry Siegel and Joe Schuster.