Greaper

A Greaper is a ghost-like creature from the game Super Mario RPG: Legend of the Seven Stars. These hooded ghouls resemble a cross between a Shy Guy and the Grim Reaper. Greapers are related to the powerful Glum Reapers. One friendly Greaper is a member of the Three Musty Fears from Monstro Town. Some of their attacks are Death Sickle and Lightning Orb. One specific Greaper also showed the ability to take the appearance of Mario.

Trivia

 * Nintendo Power forgot to list Greaper's stats in the Super Mario RPG Official Player's Guide. The reason they gave was that Greaper wasn't an enemy.