Charles Faversham

From Multiversal Omnipedia

Charles Faversham was a man who conjured up a demon in the hopes of bending it to his will, so he could create a better life for himself and his daughter Agatha. Eventually he saw how evil the creature was and went back on his deal with it, using a spell to seal it away in the attic of their mansion. Afterwards, he forbade Agatha from ever going up there. He passed away not long afterwards, without ever telling his daughter what had happened. 70 years later, the monster still lived in the attic, unaware that Faversham had died or how much time had passed, and only thoughts of revenge against its captor kept it from going insane. Even though the Ghostbusters learned the origins of the creature were due to Charles Faversham, after they defeated and captured it, they avoided telling the now elderly Agatha about her father's role in its summoning, because she had loved him so much.