These are the main cast and characters for the TV show Smallville.
1. Tom Welling as Clark Kent
Clark is an earnest young man who hasn't found growing up with superpowers easy. Intensely loyal to his friends and family, he's reluctant to take on the larger responsibilities his powers make possible if it means not being there for those he's close to. In his teen years he relied on his father's help and guidance, but after Jonathan's death Clark was forced to stand on his own. Since before high school he's loved Lana Lang, but he's found his powers are not compatible with the intimate relationship he wants to have with her.
2. Kristin Kreuk as Lana Lang
Lana, who lost her parents in the meteor shower that accompanied Clark's spaceship to Earth, started high school as an everygirl teenager, a popular girl on the cheerleading squad with the handsome quarterback on her arm. But before long she realized she was living someone else's dream, and set out in search of who she wanted to be. Along the way she went into business as co-owner of the Talon coffee shop; while studying art in France she started dating Jason Teague, only to become involved in his family's quest for a mysterious Kryptonian artifact -- and herself becoming possessed by a medieval witch on the same quest. Later Lana married Lex to protect Clark, a traumatic experience that shore away most of her innocence.
3. Michael Rosenbaum as Lex Luthor
Twisted by his father's coldness since his youth, bald thanks to the Smallville meteor shower, Lex grew up to be a bitter, driven executive in his father's sprawling company. After Clark Kent saves his life, pulling him out of a river after a car accident that should have killed Clark, Lex became influenced by Clark's positive morality even as he obsessed on the impossibilities of the accident. As their relationship became more complex, both Lex and Clark realized that Lex's dark side was gaining control, a process that accelerated after Clark, feeling betrayed by Lex, turned his back on his former friend,
4. Allison Mack as Chloe Sullivan
She's been through a lot, but she's still the perky, hard-charging young journalist she was back in season 1, when she was working on Smallville High's 'The Torch.' Even then she had plenty of connections that helped her and Clark hunt down the bad guys, and remained one of CLark's most reliable friends -- especially after Clark's transporting girlfriend exposed Chloe to Clark's secret. (She didn't let on she knew even to Clark, waiting for him to tell her.) After fighting so many "meteor freaks" she was shocked to find out she was one herself: she has the ability to heal, though at great cost to herself. Chloe has had an on-again, off-again romance with Jimmy.
5. John Glover as Lionel Luthor
An unscrupulous and especially savvy businessman, Lionel build Luthorcorp into a massive empire while molding his only surviving son into his vision of a future mogul, at the cost of love and trust. Lionel took and interest in the Kents, at one point bribing (and later blackmailing) Chloe into investigating Clark for him. Chloe instead got the evidence needed to put Lionel away for murdering his parents, but Lionel was later released, an apparently changed man. By the later seasons Lionel had become an avatar for Clark's biological father, Jor-El, but Clark was never quite sure whether he could trust this old nemesis. Lionel was killed by Lex during season 7.
6. Erica Durance as Lois Lane
Lois appeared half-way through the show's run, established as Chloe's cousin. Smart and sassy, with the tough talk of a general's daughter, Lois initially displayed little interest in journalism -- though her first trip to Smallville was to investigate Chloe's apparent death. Clark, taken aback by Lois's brassiness, developed a brother-sister-like friendship with his future partner, while Chloe gradually turned her on to journalism; after Chloe graduated they both worked together at the Daily Planet. Lois is always pushing straight for what she wants -- including at different times the editor of the Planet and Oliver Queen, whom she eventually discovers in Green Arrow.
7. Aaron Ashmore as Jimmy Olsen
Jimmy is trying to carve out a space for himself at the Daily Planet as a photographer, but he's still at the bottom of the totem pole and is willing to take big risks to make his mark. While quick to grin and a bit wide-eyed, he's not naive and is not above keeping secrets from Chloe if he thinks it will protect her. He takes a dark view of meteor freaks until Chloe reveals she has meteor powers herself.
8. Laura Vandervoort as Kara
Sent to Earth ahead of Clark by her father (Zor-El, Clark's uncle), Kara was trapped in stasis until she was released by the explosion of one of Lex's experimental labs. Not having grown up on Earth, Kara is puzzled by Clark's affection for humans and dismissive of his insistence that she hide her powers. After she rescues Lex from drowning after the destruction of his lab, he becomes obsessed with her and tracks her after she disappears, eventually finding her as an amnesiac in Detroit. Facing a deadly conflict with Brainiac, Kara seeks to ready Clark to confront him. Kara appears in season 7 and is a regular in that season only.
9. Justin Hartley as Oliver Queen
Scion of the wealthy Queen family, Oliver nursed a secret need to fight against injustice, training himself physically and using the vast resources of his family enterprises to turn himself into a vigilante crimefighter, the Green Arrow. Oliver's efforts to stop Lex's 33.1 cloning program brings him into conflict with CLark, who takes exception to Oliver's willingness to rob and destroy for a larger good. Oliver, in turn, urges Clark to leave Smallville and truly use his abilities to help mankind. While Clark hesitates, Oliver forms the Justice League with other superpowered youths (and with Chloe handling tech/sidekick duties). Oliver is a regular for much of seasons 6 and 8.
10. John Schneider as Jonathan Kent
A farmer from a long line of farmers in Smallville, Jonathan Kent is smart, hard-working, honest, courageous, and loyal -- and from the day he and Martha find and bring home a baby boy they found in a spaceship and decide to raise him themselves, he works tireless to instill these same values in his adoptive son. As he grows up and discovers he's different, Clark knows his father will be there to guide him through it. But Jonathan, drawn into a race for state senator to replace an old friend felled by a scandal, suffers a fatal heart attack (in season 5). His death has a major impact on Clark, who must leave his childhood behind and decide his role in the world.