The Amazing Screw-On Head is the title of a one-shot comic book written and drawn by Mike Mignola and published by Dark Horse Comics in 2002, starring the character of the same name.
Mignola got the idea from action figures, particularly Batman ones, which seemed to be the exact same figurines with different paint jobs. So he imagined a robot with a head that screwed onto different bodies to suit the occasion, hence "Screw-on Head".

An animated pilot, based on the plot of the comic, was made by the Sci-Fi Channel in 2006 with Bryan Fuller of Dead Like Me and Wonderfalls fame as executive producer.