Margaret Astor was a dealer of religious relics.
Background[]
The Winchesters wanted to acquire the blood of a holy man and met Margaret. She directed them to Richard Greenstreet so they could purchase the blood. She later orders Mr. Cromarty to eliminate Antonio Miele to steal the skull of Saint Peter.
She later runs an illegal auction aimed at selling the skull of St. Peter to the highest bidder. Greenstreet, however, does not give money and prefers to give it to Mr. Cromarty so that he can kill Margaret. Mr. Cromarty agrees and shoots Margaret in the back, killing her.