There are few Halloween traditions in the realm of television as reliable or long-running as the annual Treehouse of Horror episodes of The Simpsons. For almost as long as the animated series has been on the air, so too have the anthology-style Halloween episodes that see the beloved cartoon family explore all facets of pop culture, with a holiday and genre slant. The inaugural “Treehouse of Horror” aired on October 25, 1990, marking the start of a thirty-year Halloween institution on television that’s still going strong.