Mister Sinister (X-Men: The Animated Series)

Mr. Sinister was originally Dr. Nathaniel Essex, a doctor who was from Victorian London. He was married to Rebecca Grey, of Grey Hall, and was a friend of James Xavier, the family physician. Rebecca had a serious illness, which Xavier's treatments could not cure. Essex was upset that he was forbidden from treating his own wife, as it would have been considered an impropriety in Victorian times. He ran the local asylum for the physically infirm.