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.
Raj: I know. Being an astrophysicist right now is like being a rock star.
Howard: Only without the sex.
Raj: Yeah, literally, none of it.
Howard: Why don't you put her in a kennel?
Raj: Why don't you put your mother in a home?
Howard: To be honest, she'd do better in the kennel.