Grim Leecher
Grim Leechers[1] are enemies from Super Mario World 2: Yoshi's Island and its remake, Yoshi's Island: Super Mario Advance 3, where they only appear in the levels The Impossible? Maze and Mystery of the Castle? These enemies resemble purple ghosts with skulls on their faces, and their name is a pun on the "Grim Reaper" and "Leech". If Yoshi is a good distance from a Grim Leecher, they will wait until Yoshi comes near, and then hover towards Yoshi once he comes too close. If they come in contact with Yoshi, the Grim Leecher will kick Baby Mario off Yoshi's back and hop on. This will cause the game controls to reverse, and Yoshi will be colored pink (purple in Yoshi's New Island). They are referred to as "Purple Zombies" in the game's pocket guide.
Grim Leechers reappear in Yoshi's New Island behaving the same as they did before. They can be found in the level World 2-4: Beware the Boo Brigade and later in World 6-8: Baby Bowser's Castle Break-In.