Simon Helberg stars as Howard Wolowitz, the only one of the nerds that is not a doctor.  He is an engineer at Caltech and is friends with Leonard and Sheldon and frequently is over at their apartment.  Wolowitz mostly goes by his last name and still lives with his mother.

Most jokes with Wolowitz revolve around his failed attempts at womanizing, though he was given a girlfriend, Bernadette, in season three.

Howard Wolowitz Quotes

Howard: Let me try gangsta: Hells naw.

Sorry, Stallion. You're weird friend, Giraffe, is here.

Penny

TBBT Quotes

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.

James Earl Jones: Why don't you and your friends come to Comic-Con with me?
Sheldon: Really?
James Earl Jones: Of course. And San Diego is right across the border from my favorite city on Earth, Tijuana.... where I'm taking you every night!
Sheldon: Ay-yi-yi.
James Earl Jones: Ay-yi-yi. Bang. Bang.