Pickman's Model (1981)

Inspired by Lovecraft's short story, Pickman's Model is about a morbid painter named Richard Upton Pickman, who created from his fiendish brush "unbelievable loathsomeness and moral foetor." William Thurber, a student of occult art and author, becomes obsessed with Pickman and pursues him learning more and more about the source of his art until it finally consumes him.