Robo-Fiend is Ultra Lord's arch-nemesis. In the episode Normal Boy, Carl was seen with Sheen fighting with his own Robo-fiend acton figure while Sheen had one of his Ultra Lord action-figures. The evil clone version of Sheen seems to be a fan of Robo-fiend and dislikes Ultra Lord. Ironically, Evil Sheen is still wearing an Ultra Lord shirt instead of a Robo-Fiend shirt.