Dib

Dib Membrane is a big-headed kid who is a member of the F Gang. He is Zim's nemesis.

Personality
Dib is incredibly determined and intelligent, and continues to hunt the paranormal despite being put down by his peers and family. It's unknown whether or not Dib hates all aliens, or just aliens that threaten Earth (like Zim and Tak).

Trivia

 * Despite his determination, he loses far more battles against Zim than he wins. Even when he wins, his plans don't work out the way he plans them. Before the 7th or so script, his profile on Nick.com said he was never able to win.