Hunter/Awakener/Player/Ranker/etc., Gate/Tower/Dungeon/Rift/etc., as well as series that are basically the Hunter genre, that are also BL. This list includes series that I have and haven't read: if I'm missing any/added any incorrectly, or if you have any other suggestions, please leave a comment so I can fix it!

Guideverse series are included when the setting is close enough to being a Hunter story - there are Gates or other ways for things to invade from other dimensions, there's monster fighting, they're actually called Hunters, etc. Sometimes the "Hunter" setting is only a background setting and you don't actually see it much in-story, however.

Guideverse that's also Hunter/Awakener (includes series that I removed from/didn't quite qualify for this list): https://www.novelupdates.info/viewlist/108374/

For lists that include other Hunter recommendations:
Hunter series I have read or am planning to read: https://www.novelupdates.info/viewlist/87240/
Hunter series I haven't read Pt.1: https://www.novelupdates.info/viewlist/94830/
Hunter series I haven't read Pt.2: https://www.novelupdates.info/viewlist/99796/
Hunter series I haven't read Pt.3: https://www.novelupdates.info/viewlist/107529/
Hunter series I haven't read Pt.4: https://www.novelupdates.info/viewlist/110977/
Series that don't have chapters listed on this site: https://www.novelupdates.info/viewlist/91661/