Notes:

Sandy Petersen worked on Quake and some of the Lovecraftian monsters were based on the designs from 1988's "S. Petersen's Field Guide to Cthulhu Monsters: A Field Observer's Handbook of Preternatural Entities": the spawn is literally right on the cover, and Shub-Niggurath's design in the game is essentially an immobile version of the Dark Young.
Interestingly the Dimensional Shamlber is described as "This shaggy, wrinkled entity…" making the skin vs. fur debate go back 8 years before Quake was even released.