According to the Beer Advocate website , Romulan Ale from Star Trek is brewed by Cervecería Centro Americana in South Africa.
A search in Google Images will produce several images of the bottles.
I have included a link to one image.
Romulan Ale
beer.stackexchange.com/users/4437/JaneZane
While I'm not a fan Butterbeer from Harry Potter is apparently a thing.
However I don't believe it's widely available and is pretty niche by the looks of it.
beer.stackexchange.com/users/4272/Matt McCabe
Olde Frothingslosh started as a joke.
Not quite from a book, but possibly of interest.
Olde Frothingslosh Pale Stale Ale
beer.stackexchange.com/users/23/Bryan Cain
Discworld Ales have a range of drinks inspired by the Terry Pratchett novels!
I've not tasted any myself
but they were well received as a gift.
beer.stackexchange.com/users/4392/DaniloV
Duff Beer
"Duff Beer is a brand of beer that originally started as a fictional beverage on the animated series The Simpsons.
Since then it has become a real brand of beer in a number of countries without permission or consent from its original creator, Matt Groening, and has resulted in legal battles with varying results.
An official version of the beer is sold in three variations near The Simpsons Ride at Universal Studios."
- Duff Beer (Wikipedia)
beer.stackexchange.com/users/529/Wayne In Yak
Dagschotel
In Belgium, there's a tv-show that's been running for 20 years.
One of the characters always orders a "dagschotel" (french: plat du jour, english: the dish of the day) when he orders a glass of beer.
A few weeks ago, some brewery makes bottles of Dagschotel.
beer.stackexchange.com/users/4327/Natrium
In Germany there is a famous comic book beer called Bölkstoff .They also began producing it
but nowadays it's rare, but you can get it online.
There are films about Werner where he drinks this specific beer.
Rötger Feldmann is the author of these comic books and films.
You can find info here and here much more on the German wikipedia page.
If you have further questions about the films or the beer, feel free to ask.
beer.stackexchange.com/users/5734/min hundje
There is also a BreakingBad based beer that you can find here Schraderbräu is a homebrew beer brewed by Hank Schrader.
He is seen bottling the beer in Breakage, the fifth episode of season 2.
He offers a six-pack of the beer as a prize in a fundraiser in ABQ, the thirteenth episode of season 2.
beer.stackexchange.com/users/4423/Jordi Castilla
Duff  is the only one of which I am aware. I know there are  Game of Thrones  inspired brews, but are there any others that originated from works of fiction?
What other beer brands began as fictional but eventually became real?
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beer.stackexchange.com/users/4245/Valerie
A few beers started life as fictional. These include Romulan Ale from Star Trek, Butterbeer from Harry Potter, Olde Frothingslosh, Discworld Ales inspired by Terry Pratchett novels, Dagschotel and Bölkstoff . Romulan Ale from Star Trek, Butterbeer from Harry Potter, Olde Frothingslosh, several drinks inspired by Terry Pratchett novels produced by Discworld Ales, Duff Beer, Dagschotel and Bölkstoff are all inspired by fictional beers.
Romulan Ale from Star Trek, Butterbeer from Harry Potter, Olde Frothingslosh, several drinks inspired by Terry Pratchett novels produced by Discworld Ales, Duff Beer, Dagschotel and Bölkstoff are all inspired by fictional beers.