 " Treehouse of Horror " ( originally known as " The Simpsons Halloween Special " ) is the third episode of The Simpsons ' second season . It originally aired on the Fox network in the United States on October 25 , 1990 . The episode was inspired by 1950s horror comics , and begins with a disclaimer that it may be too scary for children . It is the first Treehouse of Horror episode . These episodes do not obey the show 's rule of realism and are not treated as canon . The opening disclaimer and a panning shot through a cemetery with humorous tombstones were features that were used sporadically in the Treehouse of Horror series and eventually dropped . This is also the first episode to have the music composed by Alf Clausen , taking over for Danny Elfman who also wrote the show 's theme . 
