Dib

Dib is one of the main characters from the show. Dib is always trying 

Dib
Gender	Male
Relatives	Gaz (sister), Professor Membrane(father)
Voice	Andy Berman

expose Zim for being an alien. But his reputation has cost him and nobody believes him. In the past he has claimed to see big-foot in his garage, vampire gerbils, and of course aliens. Dib has even gone as far to report all his sightings (there are a lot of them) to "Mysterious Mysteries" a show on the show...

Everyone thinks that Dib has a large head and it is full of hot air. They have even considered counseling for him. He appears in all the episodes.