Devil

The Devil, also known as Satan, is in charge of Hell. Ned Flanders has sometimes been seen as the Devil. However, there is another devil of sorts. He often appears in visions or dreams.

History
When Mr. Burns had a birthday he thanked Satan for his long life in the Springfield Shopper and a picture of him giving Satan a check for one billion dollars is printed.

Non-canon
Whenever Charles Montgomery Burns has a near death experience, Satan tries to get Burns to hell, but continually fails. He also appears as a to try and get Eve to eat an apple from the tree in  the Garden of Eden.