Rudy

Rudy, originally known as "A hidden figure", is one of Wario's enemies, appearing as the main villain of both Wario Land 3 and Dr. Mario 64. Rudy is a giant clown-like creature with green skin, a big red nose, and detached floating hands by his sides, although concept art of him as the final boss of Wario Land 3 depicted him with regular arms. He is only referred to as "a hidden figure" in Wario Land 3, later being given the name "Rudy" in the English version of Dr. Mario 64, and he is later referred to by Wario as "Rudy the Clown" in Fortune Street. In Japanese versions, however, Rudy is never referred to by a specific name, even in the Dr. Mario 64 port of Nintendo Puzzle Collection.

Wario Land 3
When Wario was trapped in the world inside a music box in Wario Land 3, a hidden figure appeared as a giant shadowy face in a temple, pleading Wario's help. He states that he is the god of this world, and an evil being sealed away his powers in five music boxes. He requests Wario to break the seal by bringing all five music boxes to him. Wario is unwilling to help at first, until he mentions that he will send Wario home when he is freed and will let Wario keep any treasures he finds along the way. After that, Wario sets out to collect the music boxes.

During the course of the game, Wario can visit a hidden figure at The Temple and be instructed with which level he has to go next in order to progress. After all five music boxes are collected, he will stop giving advice. Instead, if Wario visits him, the music boxes will play a tune that frees him. A hidden figure then turns into his true form, a giant clown with skull patterns whereupon he says that he will take over the music box's world as well as the outer world. It is later revealed that he turned all the world's inhabitants into the monsters that Wario defeated during his quest; he was using Wario to break the curse placed on him by the inhabitants of the world of the music box when he had tried to take control before.

A hidden figure attacks Wario with his hands, attempting to grab or smash Wario. The game cannot be paused during the battle like every other boss battle. Unlike every other enemy or boss in the game where each of them has at least one attack that ejects Wario from battle, if he successfully grabs Wario, the player instantly gets a Game Over, the only attack in the game to do so. To combat the boss, Wario must attack one of his hands by jumping on them, leaving them on the floor. After that, Wario has to grab the fist and throw them at his nose. After two hits, a hidden figure will grab more frequently, and he will become angry after taking three hits.

After four hits, a hidden figure is defeated, and the inhabitants of the music box world are returned to normal. They then send Wario back to his own world, letting him keep all the treasure he had found.

Dr. Mario 64
The character returns as the main antagonist in Dr. Mario 64, now officially named as Rudy. He sends his minion Mad Scienstein to steal some Megavitamins from Dr. Mario, planning to use them to cure his cold. Mad Scienstein steals the Megavitamins, but is pursued by Dr. Mario and Wario, the latter of whom wants the Megavitamins for himself. The chase led them all to Rudy's castle, where the selected character confronts Rudy, who took the bottle for himself. After Rudy is defeated by Dr. Mario, he uses the Megavitamins to cure Rudy, but if he is defeated by Wario, Rudy won't be cured as the Megavitamins are snatched by Mad Scienstein, who Wario continually chase to no end. In multiplayer modes, Rudy has the highest-level AI along with Metal Mario and Vampire Wario.

Fortune Street
Though he does not physically appear, Rudy is referenced in Fortune Street. When Wario builds a circus tent on the game board, he states "This is gonna be the best circus ever... as long as Rudy the Clown doesn't show up!"

Trivia

 * In his concept artwork, Rudy has arms. However, in the game, his hands are separate floating graphics, stated to be due to hardware limitations, as the number of graphics the arms would require would not be manageable.
 * In Wario Land 3 coverage, Nintendo Power describes the hidden figure as a "mysterious monarch."