Before I totally freak out about how much I love this show I thought I'd explain a bit about the show and it's main characters! This is from the Invader Zim Wikipedia because I'm too lazy to type it all
Zim: Overzealous, impulsive and convinced of his own greatness, Zim is incompetent as an Invader. He constantly schemes to enslave or destroy life on Earth and, despite his access to potent Irken technology, his plans, frequently based on misconceptions, are never successful.
He has two forms,His alien form and his 'human' form which is just a disguise
Zim in his 'human' form
Gir:Zim's only companion, GIR is a Standard Issue Information Retrieval unit (SIR). He was made out of some scraps in a trash bin by The Almighty Tallest. The name "GIR" is a self-applied moniker that is never explained; even GIR himself states that he doesn't know why he refers to himself as GIR. He differs physically from other SIR units in that his head contains odds-and-ends rather than artificial intelligence hardware. Because of this, GIR displays a wildly erratic personality. He is almost completely ineffective and rarely obeys Zim's commands, variously due to distraction, disinterest and disobedience. GIR disguises himself by wearing a green dog suit which fools most humans, despite looking almost nothing like an Earth dog.
Dib: Zim's main opponent on Earth. He has been obsessed with the paranormal and supernatural since he was a baby and instantly recognizes Zim as an alien, but everyone derides him as "crazy" or "insane", including his father and sister.
Gaz: Gaz is Dib's cynical, humorlessly sarcastic and psychotic younger sister. She plays a prominent role in the show, but rarely takes an active part in attempting to hinder Zim's schemes. Though she knows and admits Zim is an alien, she believes Zim is too dumb to actually be a threat. She has very few interests, primarily video games and pizza.
Almighty Tallest Red and Almighty Tallest Purple: collectively known as The Almighty Tallest, are the emperors of the Irken Empire. They are united in their love of destruction, tormenting of others, snacks, puppet shows and their hatred of Zim. The Almighty Tallest both rule the empire because they are the same size.
