Oh, there are so many gay-themed books I've read and own, listing them all would take hours.
I'll try to give you a few.
Detective stories / Crime
Michael Nava - Henry Rios series, 6 or 7 books starring Henry Rios a gay latino lawyer
Joseph Hansen - Dave Brandstetter series, about 10 or 12 books set and first published in the 1960's to 70's. Protagonist is insurance claims investigator Dave Brandstetter.
Michael Craft - Mark Manning Mysteries, 6 books so far
Mark Richard Zubro - Paul Turner Mysteries, Paul Turner is a gay detective
Mark Richard Zubro - Tom + Scott Mysteries, Tom Mason is a gay english teacher, his lover Scott Carpenter a baseball star
R.D. Zimmerman - Todd Mills Mysteries, Gay news reporter solving crimes.
Grant Michaels - Stan Kraychik Mysteries, revolving around a gay haidresser
comedy
Stephen Fry (UK author, playwrite, director and actor) The Liar
Stephen Fry The Hippopotamus
Stephen Fry Making History
Robert Rodi Closet Case
Robert Rodi Kept Boy
Robert Rodi What they did to Princess Paragon
Robert Rodi Drag Queen
Michael Carson Sucking Sherbet Lemons
Michael Carson Coming up Roses
Michael Carson Stripping Penguins Bare
These are just a few of the books I've bought over the last 2 decades. If you want more, give me a shout.
Stefan