Since it first aired in 1966, “Dr. Seuss’ How the Grinch Stole Christmas” has become a pop culture institution. It’s one of the best animated films ever made. It’s a touchstone of the holiday season. It’s a common thread for generations of movie, TV and children’s book fans.

And yet there are a few things many of us don’t know about the special. Here are five things you might not know.

Boris Karloff. Yes, everyone knows that Karloff, immortalized forever as Universal’s Frankenstein monster in the studio’s movie series from the 1930s, provided the narration and the voice of the Grinch. But most probably think that Karloff had been in hibernation for decades before recording the Grinch and then passing from this plane of existence in 1969. But Karloff was active in show business even three decades after his Frankenstein heyday. He was memorable not only as the Grinch but also for appearances on “The Wild, Wild West,” “The Girl from UNCLE” and “I Spy.” He even hosted the “Thriller” anthology TV series for two years beginning in 1960.

Thurl Ravenscroft. Possessor of one of the great names of all time, Ravenscroft was the man behind the booming bass voice who sang “You’re a Mean One, Mr. Grinch.” Because Ravenscroft wasn’t credited, many people assumed that Karloff sang the song. Ravenscroft had, up until his death in 2005, a long and varied career. He was the voice of Tony the Tiger in Frosted Flakes commercials. His voice can be heard in the Pirates of the Caribbean and Haunted Mansion Disney attractions. He had a brush with another animated pop culture franchise by singing the song “No Dogs Allowed” in “Snoopy, Come Home.”

Chuck Jones. I’m of the opinion that the “Grinch” animated show wouldn’t be half as good if not for director Chuck Jones, seen above with Karloff. A legendary animation director, Jones – who died in 2002 – directed many great Warner Brothers cartoons, including two of my favorites, “What’s Opera, Doc” and “One Froggy Evening.” Jones’ talent permeates the “Grinch” special but is especially notable in the little touches, including the expressions on the Grinch’s canine sidekick, Max.

Albert Hague. Yes, Mr. Shorofsky from the “Fame” movie and TV series has a “Grinch” connection. He wrote the music for “You’re a Mean One, Mr. Grinch.” His 2001 obituary noted that Dr. Seuss himself, Theodore Geisel, said that Hague contributed greatly to the special. “Any man who slides an octave on the word ‘Grinch’ gets the job,” Geisel said upon hearing Hague’s work.

Other Grinches. I’m not talking about the Jim Carrey movie. Two other animated specials, “Halloween is Grinch Night” and “The Grinch Grinches the Cat in the Hat,” aired in subsequent decades. Although the wonderful Hans Conried performed the Grinch in the first, neither can compare to the original special.