Update: I just updated this addon to work with Blender 2.80. You can find the source and recent readme on the github page here: https://github.com/andyp123/blender_io_mesh_bsp
The latest release supports BSP2, importing of lights for eevee and cycles, camera setup based on info_player_start and info_intermission entities, much better material setup, supporting masked emission and transparency and also imports files MUCH faster.
I also made a companion add-on for importing Quake .map files, which can be found here.
Original Post (minus pasted readme):
I’m not sure how many people here will want to import level geometry and textures from a 17 year old game, even if it is pretty much the best game ever, but I thought I would upload it just because there might be someone, or it might be useful for someone who wants to write their own mesh importer for some other game etc.
The script takes any valid Quake 1 BSP file and loads each model as a separate mesh. Quake stored textures in each .bsp file, so the textures are also loaded as materials and applied to the meshes. There are a couple of simple import options to disable creation of materials, load only the main level geometry and also a scale parameter.