The Evil Robot Helmet is the main antagonist of the Grojband episode "Helmet". The helmet is worn by Corey when his voice cracks, so the Grojband members decide to let him wear the helmet. Trina Riffin sets the helmet to "Bad Mode", causing the helmet to possess Corey and turn evil. The Grojband members manage to pry the helmet off Corey but the evil helmet flies away to a carnival, and while the Grojband members fight the helmet at one point, Kin knocks the helmet toward a ferris wheel, causing the helmet to fuse with it to create a giant robot body for it. After Trina calms down from her "Happy Diary Mode," the Grojband members get her diary as lyric inspiration for their song, causing the robot helmet to get destroyed and explode after listening to the lyrics.