Guardian Angel

The Guardian Angel was a demonic entity which appeared in the Adventure Time episode Dungeon.

Description
At first appearing as an angelic female creature complete with flowing white robes and expansive, feathery wings, once it revealed its true intentions it's visage changed to that of a demonic skull.

History
When Finn was being hunted by the Demon Cat in the Crystal Eye Dungeon, the Guardian Angel arrived to carry him away. Healing the battered boy from all of his injuries, the Angel then showed its true colours and dropped Finn into a caged pot in order to cook him into a soup. Fortunately for Finn, the Guardian Angel had already captured Jake, and together the pair were able to break free of the cage and bring it crashing down on the demonic creature's head, presumably killing it.