McCay intended his Rarebit Fiend strip to be an amusing morality play, meant to comment on the dangers of overindulgence. It focuses on various people who have a passion for a piece of foodstuff called a "rarebit." The strip takes place after the Rarebit Fiend (who is never named in the comic strip) has eaten a rarebit. It causes him to have strange dreams and nightmares, thus exacting the price for his folly.
Film pioneer Edwin S. Porter produced a film version of Dream of the Rarebit Fiend in 1906, though this is not considered to be a true "animated film" but rather an early exercise in trick photgraphy.
McCay's famous character Little Nemo first appeared in Dreams of a Rarebit Fiend within the first year of its existence. Unlike Rarebit Fiend, which was intentionally created for an adult reading audience, Little Nemo was intended for children. McCay went on to write and draw Little Nemo for the New York Herald.
McCay produced four hand-drawn animated films based upon his Rarebit Fiend, all within the same year (1921):