Lana Lang (Krisitn Kreuk) was introduced since the pilot of Smallville as a potential love interest for Clark Kent.  During the first season she's dating Whitney Fordman, but by season two she and Clark grow closer.  He eventually pushes her into the arms of Lex Luthor by hiding secrets about his true identity.  However, the soon rekindle things just before Lana is set to marry Lex.  Eventually, Lana realizes the only way for Clark to be the best superhero would be if she left Smallville.  She left the show as a series regular.

Lana Lang Quotes

Young Lana: Do you want to make a wish?
Martha: I would love to make a wish.
Young Lana: Okay. Abracadabra.

(to Clark) Sometimes I dream I'm at school, waiting for Nell to pick me up. But she doesn't come, so my parents drive up. They're not dead, they're just really late. Then I get in their car and we drive back to my real life in Metropolis. That's usually when I wake up. But for a minute, I'm totally happy, until I realize I'm still alone.

Lana

Smallville Quotes

I'm about as real as it gets.

Chloe

Clark: My father says you learn more about yourself when you lose.
Lex: What'd you learn?
Clark: That I'm not destined to be a politician. You need two different personalities.
Lex: You don't need to be an elected official to change the world, Clark.
Clark: Have you ever thought about getting into politics?
Lex: Someday I'd like to be president.