Everyone knows that the Grinch didn't care much for Christmas, but how did he feel about Halloween? We just learned that he spent All Hallows' Eve terrorizing the fine citizens of Whoville, thanks to Insider, who spotted this lesser-known prequel to How the Grinch Stole Christmas.

Titled Halloween is Grinch Night, the short animated movie ran as a television special in October 1977. Although it was designed to be a prequel to the classic Christmas special, Dr. Seuss wrote it 20 years after How the Grinch Stole Christmas, which was published in 1957.

The TV special opens with the Whos of Whoville cheerfully going about their business … until they catch a whiff of the "sour sweet wind," which tips them off that the Grinch is coming to town. The word "Halloween" is actually never spoken in the movie; it's replaced by the term "Grinch Night" throughout. Instead of a sleigh, the Grinch descends on the town with a wagon full of monsters pulled by Max. And instead of Cindy-Lou Who coming to the town's rescue, it's a little boy named Euchariah who intervenes.

In addition to the Halloween prequel, another TV special called The Grinch Grinches the Cat in the Hat aired in 1982. Although both of these specials won Emmy Awards, their impact wasn't as long-lasting as How the Grinch Stole Christmas, which was adapted into a live-action version starring Jim Carrey in 2000, and again in 2018 with a 3D animated version called The Grinch, with Benedict Cumberbatch voicing the title character.

Check out the Halloween-themed prequel in the YouTube video below, or get all three specials on Amazon with the Dr. Seus’s's Holidays on the Loose ultimate edition DVD.

[h/t Insider]