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.
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.
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.
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.
If you have further questions about the films or the beer, feel free to ask.
"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)
Olde Frothingslosh started as a joke. Not quite from a book, but possibly of interest.
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.