Mad Scienstein is an enemy found in Wario Land 3 and Dr. Mario 64 that assists Rudy the Clown. Mad Scienstein's only main attack is throwing magic potions at Wario to turn him invisible, allowing him to go through security gates. Unlike many other enemies in Wario Land 3 which were transformed into creatures by Rudy, Mad Scienstein appears to have not been transformed in any way, due to his human-like appearance.
Mad Scienstein reappears in Dr. Mario 64 as Rudy's minion where he wants Mad Scienstein to cure his cold so that Mad Scienstein must steal some to cure his cold. Dr. Mario, along with Wario, follow them and fight various enemies from Wario Land 3 until reaching Mad Scienstein and his boss Rudy. They manage to defeat them and cure Rudy's cold. Mad Scienstein is also playable in this game.