Fiend Folio

The Fiend Folio was a Monster Manual-like book for Advanced Dungeons & Dragons 1st edition. It served to gather up the various monsters that had been submitted to TSR works but not made the MM itself as of its 1978 edition - for instance, kuo-toa, svirfneblin and of course the official full writeup of drow. Most came out of White Dwarf's Fiend Factory as of then. Many of the latter monsters are laughable crap, like the Xvart which sounds like Fart, so have fallen into obscurity or - like the Flumph - notoriety.

But a few gems do appear amongst the dross: usually cited here, Charles Stross' badass Githyanki and Githzerai. We could also shout-out to the Dark Ones, the Creepers and Stalkers. Who knows why later publishers didn't publish stuff featuring those guys, they were fucking sweet.

A 3rd-party company called Necromancer Games vaguely affiliated with White Wolf released a spiritual successor to the Fiend Folio in "The Tome of Horrors", which adapted many, if not all, of these monsters to Dungeons & Dragons 3rd Edition. WotC for 3e did its own Fiend Folio, figuring that was a decent brand for niche monsters - so Caryatid Columns and those Dark Ones were here. Others were brought back for Pathfinder. With the release of Dungeons & Dragons 5th Edition, many of these monsters are starting to be revived and return to the spotlight. The Lava Children, Flumph, and Berbalang all entered the canon here, among others.