Furfur

In demonology, Furfur (other spelling: Furtur, Ferthur) is a powerful Great Earl of Hell, being the ruler of twenty-six legions of demons. He is a liar unless compelled to enter a magic triangle where he gives true answers to every question, speaking with a rough voice. Furfur causes love between a man and a woman, creates storms, tempests, thunder, lightning, and teaches on secret and divine things.

He is depicted as a deer or winged deer, and also as an angel. To some authors he changes from deer into angel when compelled to enter the magic triangle.

Furfur in Latin
'Furfur' or 'furfures' in Latin means "bran". However it seems more likely that the name is a corruption of 'furcifer', the Latin word for scoundrel.