The Angel Mummy is a boss in Castlevania II: Belmont's Revenge. It is a three-headed monster whose body is comprised by the bones of many different creatures. It attacks by throwing the neck/spinal bones from one of its heads to another and also spews deadly projectiles from the main head's mouth.
The Angel Mummy is the boss of the Cloud Castle. It is a huge monstrosity composed of what appears to be a big human head bearing two other smaller skeletal heads, one above and one below. These are essentially two bound White Dragons; the upper one having a human skull and the bottom one having a dragon skull. Each head attacks by spewing fireballs and hurling their neck bones forward in a boomerang-like manner, which then return to reassemble on the other head's neck. The boss can only be damaged by attacking either one of the heads.
The North American instruction booklet for Belmont's Revenge mistakenly states the Angel Mummy is the boss of Plant Castle, while it's actually the boss of Cloud Castle.