Hunter/Gate/Etc. series, as well as series that are basically the Hunter genre, that are BL. List includes both series that I have read and series I haven't read. If I'm missing any/added any incorrectly, 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.

For lists that include non-BL recommendations (there may be some overlap with this one):

List of Hunter series I have read or am planning to read: https://www.novelupdates.com/viewlist/87240/
List of Hunter series I haven't read: https://www.novelupdates.com/viewlist/94830/
List of Hunter series I haven't read Pt. 2 (no BL this time!): https://www.novelupdates.com/viewlist/99796/
List of series that don't have chapters listed on this site: https://www.novelupdates.com/viewlist/91661/