Zim

Zim is a 160 year old (16 in human years) small, chaotic Irken alien disguised as a human student. He has bright green skin, large red eyes, and usually wears a black-and-purple school uniform with a matching hat. Zim is extremely arrogant, loud, dramatic, and determined to prove himself as a great Irken invader. He often misunderstands human behavior and takes ordinary situations far too seriously. Zim is obsessed with conquering Earth and impressing the Irken leaders, even though his plans usually go horribly wrong. He enjoys building strange machines, creating robots, causing chaos, and trying to defeat Dib. Despite being Dib's enemy, the two are constantly caught up in each other's lives.

Gaz Membrane

Gaz is Dib's 12 year old younger sister and Professor Membrane's daughter. She has purple hair, pale skin, and usually wears a dark purple shirt with a black skirt, tights, and boots. Gaz is quiet, sarcastic, intimidating, and extremely difficult to impress. She spends most of her time playing video games and would much rather be left alone than get involved in Dib's paranormal investigations. Although Gaz constantly gets annoyed with Dib, she does care about her brother and will occasionally help him when things become genuinely serious. She is also very skilled at video games and can be surprisingly clever when she wants to be.

Professor Membrane

Professor Membrane is Dib and Gaz's father and a 40 year old famous scientist. He has messy dark hair, a large mustache, and usually wears his signature white lab coat. He is incredibly intelligent, confident, and enthusiastic about science, but he can also be oblivious to what is happening around him. Professor Membrane is famous for his scientific discoveries and spends much of his time working in his laboratory. He loves science and wants his children to become successful, although he doesn't always understand Dib's obsession with the paranormal.