Prof. Chromedome was a scientist who worked for Chairface Chippendale. He had green skin and a metal skullcap (hence his name). Chromedome is the one who created the Awesome Heat Ray for Chairface's birthday party, then combined it with the stolen Geissman lenses and used its deadly beam to carve Chairface's name on the moon. He was stopped by Arthur, who, after shining a flashlight into Chromedome's eyes gained control of the Awesome Heat Ray, and Chromedome was knocked unconscious when the barrel of the weapon collided with his metal head.
Later, Chairface sent Chromedome to disrupt the Mad Science Fair and steal J.J. Vatos' mind-swapping device. Chairface would've done it himself, but he hated public appearances. Chromedome himself, meanwhile, relished the opportunity to disrupt the fair, as he believed science was no fun unless somebody got hurt. In stealing the mind-swapping device, Chromedome accidentally activated it, swapping his mind, and everyone else's, with everyone else. Chromedome ended up in the body of Carmelita Vatos.
Eventually Chromedome ended up in the body of the Tick, and escaped back to Chairface's mansion with the mind-swapping device. There, he and Chairface switched bodies, with Chromedome being driven almost insane trying to figure out how Chairface's chair head was capable of speech. Both of them were returned to their original bodies after the Tick and his allies defeated Chairface.