I'm thinking we should have a central post for all the book sublemmys so we can easily find them. The ones I'm aware of are:

• !Literature@beehaw.org (defederated so only Beehaw users will work here)
• !ScienceFiction@lemmy.ml
• !Socialistbooks@lemmygrad.ml
• !Fantasy@lemmy.ml
• !GayFiction@lemmy.world
• !SapphicFiction@lemmy.world
• !Nonfiction@lemmy.world
• !StephenKing@mander.xyz (cr. mizu6079)
• !Manga@lemmy.ml (cr. AWanderingsorcerer)
• !Comics@lemmy.ml (cr. AWanderingsorcerer)
• !Comicbooks@lemmy.world (cr. AWanderingsorcerer)
• !Books@oceanbreeze.earth
• !literatur@feddit.de (cr. Communist)
• !horrorlit@lemmy.ml (cr. Lazycog)
• !Books@lemmy.world
• !Audiobooks@lemmy.ml
• !Books@group.it
• !Books@kbin.social
• !Audiobooks@lemmy.fmhy.ml
• !Books@chirp.social
• !Freebooks@lemmy.world
• !LitRPG@lemmy.ml
• !comicbooks@lemmy.world
• !horrorlit@lemmy.ml
• !cosmere@lemmy.ml
• !Reads@lemmy.world

Fediverse:

• !comics@a.gup.pe (cr. Yuki)
• !comics@chirp.social (cr. Yuki)
• !webcomics@a.gup.pe (cr. Yuki)
• !webtoons@a.gup.pe (cr. Yuki)
• !books@a.gup.pe (cr. Yuki)
• !books@chirp.social (cr. Yuki)
• !bookstodon@a.gup.pe (cr. Yuki)
• !writers@a.gup.pe (cr. Yuki)
• !SFFBookClub@a.gup.pe
• !books@kbin.social

Sublemmys in other languages would be great to add here too! I'll keep adding more as I find them.