Grand Theft Auto is a widely successful video game series…having made billions with probably millions of players.
Only exists as a video game series… no tv shows, no movies, no comics, etc.
Free Guy doesn’t count? 
The Bloom County Christmas special A Wish for Wings that Work is still one of my favorites. Robin Williams and Dustin Hoffman in uncredited roles makes it even better.
I remember that, but it’s been ages. There was also a record (I think it may have been included with one of the Bloom County books) attributed to “Billy and the Boingers”. And of course I had a “don’t blame me, I voted for Bill and Opus” t-shirt.
There are a lot of other media that we may not think of very often. The Flintstones have been adapted to vitamins and cereal.
So how did they pronounce that?
I had one with the Starchair Enterpoop and the words “Ahead Warp Zillion”.
I’m not sure if I would count merchandising as a medium. However, Flintstones has been both a comic and a live-action move.
Lots of stuff has been adapted to comics that people might not be aware of. For instance, there are Stranger Things comics.
In the future every pop culture will be adapted to another medium for 15 minutes.
Mole-ster.
It was a family special!
I’m not surprised there was a comic, and I’d forgotten about the movie.
I sometimes wonder how many of the kids eating Fruity or Cocoa Pebbles have any idea who those two guys on the box are.
If a roadside attraction counts as “another medium”, the Flintstones have been adapted in the form of Bedrock City in Arizona.
Would a Weird Al parody count?
There used to one of those in Kelowna BC. Closed 4-5 years ago.
And in 15 minutes. It used to be that cross-medium adaptations took years to be generated. Nowadays, they often plan all kinds of cross-medium promotions even before the initial release has been seen by a single member of the public.
I took a look at a list of the best selling books of the 20th century. All of the top ten have been made into films. Catcher in the Rye is #12.
#11? That’s Paulo Coelho’s O Alquimista (The Alchemist). I’ve read it. A curious philosophical fantasy that’s sold tens of millions under the radar. Well, Goodreads has almost three million ratings. People have read it and it’s been translated into every language except Volapük. No adaptation comes up under IMDB, although one may be in preparation. The book is all talk and atmosphere making a screenplay near impossible. There was a graphic novel, though.
Not to get morbid about it, but let’s see what happens after Watterson dies. I mean, it’s not like his widow would be Courtney Love, but if Kurt Cobain’s legacy can get sold out, so can Watterson’s. Never say never.