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

Let's go smooch some rich, wrinkled toucas.

Howard

Howard: Now, I downloaded an app that might be helpful in this situation.
[whip cracks]
Sheldon: You're right. I'm smart as a whip. I should be able to figure this out.

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.

Sheldon: Why do people cry at weddings?
Mary: They're practicing for what's coming later.