The performance of the song, "You're a Mean One, Mr. Grinch," is often attributed to Boris Karloff, who narrated the How the Grinch Stole Christmas! cartoon television special. However, the singer is actually Thurl Ravenscroft. (Source.)

Theodor Seuss Geisel once remarked, "If I were invited to a dinner party with my characters, I wouldn't show up." In the case of the Grinch, we can't say we really blame him. (Source.)

At the time that How the Grinch Stole Christmas! was written, Dr. Seuss was 53 years old… which if you'll remember is the exact same age as the Grinch. (Source.)