The Craniacs are a series of robot drawings created by Rudy that are obsessed with collecting futuristic devices, and dwell in The Futuredome. Whenever a new Craniac appears, the last version is deemed "obsolete". The obsolete Craniac is then shut down and put into a freezing tube to keep it in a cryogenic stasis.
There are 4 versions of Craniac; they are Craniac 1, Craniac 2, Craniac 3, and Craniac 4, who was drawn by Rudy to shut down Craniac 3. Craniacs 1, 2 and 3 are deactivated and frozen. Craniac 4 became an ally with Skrawl in "Double Trouble", as Skrawl needed the aid of Craniac 4's futuristic technology to create a robotic clone of Rudy.