Tonight, one of TV’s longest-running Halloween traditions will come again, as the 36th Simpsons “Treehouse of Horror” special airs at 8pm EST on Fox. In the decades since the first “Treehouse” premiered on October 25, 1990, the episodes — which see Simpsons characters parody various horror (and occasionally non-horror) classics, accompanied by a spooky couch gag or wraparound story — have become beloved not just by TV fans, but horror fans as well, including Academy Award-winning horror auteur Guillermo del Toro, who created the opening sequence in 2013. But as the first episode was being filmed, series creator Matt Groening anticipated none of that — in fact, he worried that the original “Treehouse of Horror” segment parodying Edgar Allan Poe’s “The Raven” was “the worst, most pretentious thing [the show had] ever done.”