Signor Screwup, also known as ‘the Anti-Inventor’, was a robot-like being in Gyro Gearloose's dreams.
Signor Screwup was, to a child Gyro Gearloose's imagination, a robot-like demon made of discarded mechanical parts, whose purpose was to unmake Gyro's inventions while he was sleeping. Gyro often had nightmares about Signor Screwup, a fact which he recalled in 1996, when Donald Duck asked him if he had ever had nightmares as a child.
Behind the scenes
Signor Screwup first appeared in 1996 in The Isle of Can't-Be-Can.