Doom Beastiary (sic) is a website which contains Doom monster information. The site was created and is hosted by Nick "NiGHTMARE" Baker. Submissions of new monsters from contributors, though usually one image and not an entire sprite set, are also accepted.
Unfortunately, the site has not been updated since December of 2003, and appears to be inactive. Daniel "Tormentor667" Gimmer created his Realm667 Doom Beastiary in 2007 as a monster resource site and an homage to Nick Baker's Beastiary.