I have not watched Big Bang Theory for about a year now because I barely watch TV, but when I did watch it, I'd have to say Penny's girlfriend, Zack. Something about him made me like him, probably his goofy attitude, and how he didn't know anything at all. He was not what I thought he was, which was a strong person who would beat anyone who made fun of him. Fortunately, the writers didn't make him that way, and made him tell funny, but stupid jokes.