Author Avatar: The Grinch to Dr. Seuss, not only because he was also a recluse. Seuss's house and studio were on a hill in California and, every Christmas, would look down with distain upon the houses covered in cheesy lights and decorations below him. Even more significantly, the Grinch mentions that "for fifty-three years I've put up with it now"; Suess was 53 when he wrote the book.
Disowned Adaptation: Dr. Seuss himself did not like the end result of the cartoon much, citing it as having too much of Chuck Jones' own art style. He much preferred the later Grinch (and other Seuss-inspired) specials that were created by Friz Freleng.
Channel Hop: Originally run on CBS for over 30 years, ABC got the special during the Turn of the Millennium and would often run it in double-features with the 2000 film. In 2015 the rights went to NBC, making it possibly the first Christmas special to have been on all of the original Big Three networks at some point or other.
Distribution-wise, the special originally belonged to MGM Television, but was a part of the library Ted Turner purchased along with MGM in 1986 (having only kept MGM itself for 74 days, but kept the library afterwards). As a result, it fell under Turner's in-house distribution firm until 1996, when the Tuner-Time Warner merger occurred and Turner Entertainment was absorbed into Warner Bros., who have since held the rights; since 1986, TBS, TNT and later Cartoon Network have broadcast the special on cable.
Edited for Syndication: For many years US network broadcasts deleted one of the "You're a Mean One" verses ("You're a rotter, Mr. Grinch...") as well as a genuinely disturbing moment in which the Grinch does his Slasher Smile while leering at several young Whos in their bed. Later ABC broadcasts, and 2015 NBC airings, cut the special down to the bare minimum to make room for more ads, keeping the important story parts, deleting many of the visual gags, as well as a shot of the Grinch cracking his whip while Max pulls the sleigh up Mt. Crumpet. Averted with broadcasts on the Turner networks such as TBS and Cartoon Network, which show the special uncut, probably due to being cable networks that can make revenue off cable subscriptions in addition to ads (plus owning the special helps- see above). NBC also restored The Grinch to its original runtime in 2016, in honor of its 50th anniversary.
According to Chuck Jones' daughter Linda, the original idea was to have Boris Karloff narrate, voice the Grinch, and perform the song "You're a Mean One, Mr. Grinch", that is until Karloff informed Jones he can't actually sing, thus paving the way for Thurl Ravenscroft. Stage productions, and the live-action film would keep the idea of the Grinch's actor singing it though.
Adored by the Network: And how. Freeform (as ABC Family) loved playing this movie during the 25 Days of Christmas event. For 2016, however, the cable rights were reclaimed by HBO, putting an end to their Grinch obsession.
Dyeing for Your Art: Jim Carrey found the mask to be horrifyingly claustrophobic and the yak hair used in the suit was constantly itching his skin. It got to the point where an interrogation expert who specialized in training special forces to endure torture had to be brought in to help Carrey cope. The expert's suggestion was for Carrey to distract himself from the discomfort was to smoke constantly and to eat everything in sight, which Carrey did throughout production.
Tim Burton was offered a chance to direct the Live-Action Adaptation, but could not due to a conflict with another project (presumed to be what would become, many years later and without his involvement, Goosebumps) he was working on at the time.
For fans of Space Ghost Coast to Coast, it was disappointing that George Lowe didn't narrate the film and only narrated the video game. Imagine Space Ghost narrating The Grinch; admit it, that would've been awesome.