Monica Geller is a little bit crazy, but definitely seems to be the leader of the group of Friends.  She's Ross's sister and high school best friends with Rachel and kind of ties to the group together as a mother-like character.

Monica is known for being a little OCD and for being overweight in high school.  Now?  She's a bit of a chef but holds various jobs during the season.

At the end, Monica ends up marrying Chandler in season seven.

Monica Geller Quotes

Monica: What's "PLEH?"
Joey: That's help spelled backwards so that the helicopters can read it from the air!
Monica: Ah...what's doofus spelled backwards?

(To Julio) Your a poet and don't know it.

Monica

Friends Quotes

Monica: What's "PLEH?"
Joey: That's help spelled backwards so that the helicopters can read it from the air!
Monica: Ah...what's doofus spelled backwards?

I'd like to believe that when the right woman comes along, you will have the courage and the guts to say "No thanks, I'm married."

Chandler