Zombie Wario

Zombie Wario, also known as Ghoul Wario , is one of Wario's transformations in Wario Land II, Wario Land 3, and Wario Land 4. This undead alter-ego is triggered by being touched by a zombie (Wario Land II and Wario Land 3), touched by a ghost (Wario Land II), spat at by a Skeleton Bird (Wario Land 4), or coming in to contact with Cractus's drool (Wario Land 4). When a zombie, Wario is impervious to all enemy damage, can defeat almost all enemies on touch, and fall through thin floors, making it quite useful at times. Unfortunately, he moves at a very slow speed, can barely jump, but he cannot jump higher unlike his normal form (in his first appearance in Wario Land II, he could not jump at all), and often his ability to fall through thin platforms is used to hinder him. To return to his normal form, Wario must walk into light or fall into a body of water. He also sometimes falls apart and then might come alive again.

Zombie Wario appears once in Super Mario-Kun. Wario transforms into Zombie Wario by Cractus's drool. Sunlight reverts him to normal.

Wario Land 4

 * Nintendo 3DS Ambassador Program digital manual bio: "Press to move and  to jump. You will be able to defeat some enemies you previously could not. You will also be able to slip through certain floors."

Trivia

 * The artwork of Wario Land II and Wario Land 4 show Zombie Wario lacking shoes, though his in-game sprite shows him wearing shoes. This is referenced on the Japanese website of the former, where Wario claims that the reason he walks slow as a zombie is because he wants to watch his step without shoes.
 * The artwork of Wario Land II shows Zombie Wario's skin only looking slightly off; however, his in-game sprite shows him white as a sheet. In the Game Boy Color re-release, Zombie Wario's in-game sprite instead shows his skin as a darker orange, and in Wario Land 3, a darker green. In Wario Land 4, although the artwork shows Zombie Wario's skin with a purple tone, the in-game sprites show his skin with a green tone.