Saturn

Manga
Lord Satan was a robot created by a corrupt businessman named Hydo, Lord Satan was designed by based on the devil of legend from the fairtales and was created to bea cruel formeman and boss around the fairy tale themed robots in the Fairytale section of Wonder Island. He was designed to be cruel to the robots, but nice to the humans. However one night a robot swan named Princess Odette flew to Astro's house, after finding her Lord Satan appeared on a robot dragon to reclaim her. At First Astro was against it and tried to protect her until Lord Satan convinced Dr. Ochamizu to side with him and Hydo claiming Astro was harboring Hydo's property illegally. When Astro flew to Wonder Island he discovered that Hydo and Satan were enslaving the robots and forcing them to live in fear. Lord Satan knocked Astro out and overpowered him. It was discovered that Hydo and Satan were illegally producing weapons using the robots for manual labor. After his master Hydo was able to convince Dr.Ochamizu and  Mr. Mustachio to destroy Astro they were stopped by Kenichi and Astro's classmates who revealed the truth. After Astro was revived he was able to over power Lord Satan. While the other robots rose up and took down Hydo. Although he was destroyed his character design reappears again as the robot wrestler Saturno in Episodes 81: Mystery at Amless Dam and 96: The Might Mite from Ursa Minor.

1980's series
In the 80's Cartoon Satan was called Baron Von Hoodwink who was Dr. Magico's robot who kidnapped Princess Lollipop and punishes the other robots in the melting. Astro Boy rescued the princess and vanquished Baron Hoodwink and Firesnout, the robot dragon, all the robots turned against Dr. Magico. Baron Hoodwink only appeared in Episode 9: Hullabaloo Land.