GO-4 (GO-FR) units are robots built by the Buy 'N' Large Corporation tasked with overseeing security operations aboard spacecraft, as well as handling other miscellaneous tasks. They're the secondary antagonists in WALL-E.
They're quite small, and easily recognizable due to the red police light atop their bodies. GO-4 units are equipped with two salute-ready arms and an anti-gravity stasis beam. For communication, the units have various beeps and other sounds. GO-4 units also can deliver coffee to superiors.
A GO-4 unit served aboard the Axiom as the Captain B. McCrea's first mate, and helped Auto in his attempt to carry out Directive A-113. He was accidentally destroyed when he attempted to assist AUTO in taking down Captain B. McCrea and was kicked and sent flying through a window and crashing down near one of the swimming pools in the Lido Deck.
GO-4 used his personal elevator system to move fast around the Axiom. The entrances/exits of the elevator were usually at Steward Kiosks, the places where SECUR-T (Steward bots) were waiting inactive until they were needed. The elevator also granted GO-4 an access to the captain's quarter.