Cheers did this a few times, but I don’t recall the celebrities being jerks; it was usually the cast that looked foolish around them. (Tip O’Neill, Dick Cavett, Wade Boggs, Alex Trebek).
There was the one episode with Kevin McHale, who wound up costing the Celtics a game because he was counting the rivets in the parquet floor at MSG.
My OP was to see if Larry Sanders was the origin of a particular plot device, a celebrity playing themselves but negative fictional version for laughs. I don’t remember any of the guest stars on Cheers being portrayed negatively.
Heck, in that vein, Carl Weathers played a hilariously thrifty version of himself across several Arrested Development episodes. Tobias hires Weathers to be his acting coach, but Weathers’ advice is largely about getting your meals from the craft services table in order to save your per diem.
Not before, but Billy Crystal and Josh Gad, played themselves in a sitcom on FX last season called the Comedians about Billy and Josh starring in a sketch comedy show on FX. It was very good, and many episodes did not portray either one of them in a positive light.
Neither do I, which is why I wrote “I don’t recall the celebrities being jerks.” 
Didn’t Frank Sinatra play himself as a Mafia boss in Cannonball Run II? My memory of that movie is, thankfully, very vague. But ISTR him being the top Mafia guy in the movie, who everyone was afraid of. IMDB has him credited as just “Frank”. So, he played himself as the mobster a lot of people thought he was to begin with. Not sure if that fits your criteria.
Mel Tormé’s appearances on Night Court were played for laughs. Mel often acted vain and immodest about his status as a celebrity and usually ended up as the victim of Harry"s attempts to befriend him and express his admiration for him.
John Malkovich played a mildly unflattering version of himself in Being John Malkovich (1999).
I couldn’t remember so I went back and found it.
He is playing himself with just a hyped up version of the Chairman of the Board. He is not playing a mafia boss.
I loved that show. I was amazed that he would actually do it.
By the way, the entire series is now on Netflix, in the correct order and including the episodes that ABC never aired. ABC aired the episodes in a weird order and never showed the last few.
In the TV series It’s Like, You Know . . ., Jennifer Grey played herself. The show didn’t last for very long, but she was one of the stars of it. Much of the point of her playing herself was that in real life she had had a nose job several years before which had pretty much destroyed her career. She looked so different that nobody recognized her. The point of her being part of the group of friends on the show was that she was no longer a star and now hung out with regular people because she had nothing else to do. Interestingly, the role was originally offered to Jennifer Beals, but she didn’t want to think of herself as a faded star.
Wheaton’s appearances on The Big Bang Theory have sort of the same point. The idea is that a fair amount of people disliked his role on Star Trek: The Next Generation and he didn’t become a big star after that. The idea here is that he is now at the point that he hangs out with regular people.
Well, for non-laughs, Tony Curtis put in an interesting turn as the anti-hero in “The Boston Strangler” (whoa what a strange ending that one had).
Wonderful-as-goo Susan Dey a.k.a. Laurie Partridge played a fatally abusive mom in “Sad Inheritance”
Ted Danson also played a monstrous parent “Something About Amelia”.
Can-do-no-wrong Dick van Dyke played a (possibly semi-auto-biographical?) role as a hopeless alcoholic in “The Morning After”. Whoa a major bring-down for this 10-year-old Dick Van Dyke Show fan to see when it came on tv back then, especially the scene where a handheld camera follows him rushing into a bathroom where he pukes blood in the sink…and another scene where he wakes up on the beach and promptly goes into a delirium tremens attack and runs frantically into the water, thrashing and yelling spastically. Good times.
Can-do-even-less-wrong Robert Reed a.k.a. Mike Brady was vaguely mind-blowing as an obsessed obscene phone-caller in “The Secret Night Caller”. His breaking down in tears with his daughter, at the end (saying “I have to go live in a santarium”), was well, um, something you have to see.
In a slightly funnier vein, I enjoyed seeing an extremely pissed Tom Petty getting in a scuffle with Darth Brooks in “Sanders”. And Martin Short as Uncle Jack in “Arrested Development” was quite heartwarming. (as well as Charlize “Married! Married! Married!” Theron as Rita)
Don’t forget Merv Griffin’s cameo as himself in *The Man With Two Brains *(1983). There can’t be many with a worse image than that.
Snooker champion Steve Davis appears as himself in “The Increasingly Poor Decisions of Todd Margaret”. At one point Davis (who is apparently a mild-mannered and pleasant bloke) gets so incensed at Todd’s mispronunciation of “snooker” that he beats him up with his cue. He is subsequently admonished by another character: “You’ve really let yourself down today, Steve Davis.”
Just thought of George Burns and Gracie Allen, whose popular TV show ran for eight years in the 1950s, with radio before that. I wouldn’t say these were “unflattering” versions of themselves even though Allen played a “Dumb Dora” type.
Depending on which came first, Robert Altman’s film The Player had a lot of celebrities playing themselves (Burt Reynolds, Jill St. John, Rod Steiger, Robert Wagner, Robert Wagner, etc…) and it’s been a lot of years since I saw the film in the theater (24 to be exact) but I do recall some scenes where the celebrities are acting like jerks. This movie was released in 1992 the same year that Larry Sanders premiered, so I’m not sure which would get credit for doing it first.
Orson Welles guest-hosted the Jack Benny Program on radio sefveral times. Welles played himself as an egomanical director trying to make a movie that “deals with everything that ever happened.”
And how do we count Kareem Abdul-Jabbar in Airplane! playing a character who finally snaps at little Joey, who’s insisted all the time that he really IS Kareem Abdul-Jabbar?
[QUOTE=Roger Murdock]
LISTEN, KID! I’ve been hearing that crap ever since I was at UCLA. I’m out there busting my buns every night! Tell your old man to drag Walton and Lanier up and down the court for 48 minutes!
[/Quote]