GIR is the insane, hyperactive robotic assistant of Zim and the closest thing the incompetent Irken has to a friend, having been constructed from scrap parts and given to Zim by the Almighty Tallest just before it was handed to Zim, instead of a regular SIR (Standard-issue Information Retrieval Unit).

GIR is voiced by Rosearik Rikki Simons, and played a main role in three episodes: "Invasion of the Idiot Dog Brain", "Walk of Doom" and "GIR Goes Crazy and Stuff", and played minor or secondary roles in almost all other episodes. He was voiced by Wasabi Mizuta in the Japanese dub and Irwin Daayán in the Spanish dub.