Halloween Is Grinch Night (titled It’s Grinch Night for the 1992 videocassette release and Grinch Night for the sing-a-long videocassette release) is a 1977 children’s animated Halloween television special and is a prequel to the 1966 television special How the Grinch Stole Christmas! It premiered on ABC on October 28, 1977.

Saw this on Lemmy c/TIL and had to post it here. Never knew this existed! I assume it’s terrible and that’s why no one’s ever heard of it, but I’m still going to try and look it up when I get home tonight.