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.
Look, Leonard. There's a bridge. Drive off it.Howard
Howard: Wait. Wait. If it wasn't for Indiana Jones, the ark would never have ended up at the warehouse!
Sheldon: (gasps) That's true! He collected and delivered the ark to the proper authorities for filing.
Raj: Like a hero.
All: Yeah! Right! Yes!
Leonard: Although, technically, Indy was supposed to take the ark to a museum to be studied. He couldn't even get that done.