Fiend Factory
Fiend Factory was an article series that ran in the early issues of White Dwarf, in the days when that magazine was devoted to all manner of RPG systems prior to Games Workshop founding its own multiverse of game systems and thus turfing out rivals to focus on their own product. The Fiend Factory was a series connected to Dungeons & Dragons, and was a place where fan-submitted monsters would be edited and then printed for the perusal and interest of players and Dungeon Masters across the world. A surprising number of fan-favorite D&D monsters got their start here, and the splatbook "Fiend Folio" was actually intended to be something of a Greatest Hits Collection of submissions to this article series.
Considering how that book is received... yeah, you have been warned in terms of quality.
Its precursor was "Monsters Mild and Malign", which only ran two articles in total in White Dwarf issues #4 and 5, before being renamed to the arguably catchier Fiend Factory. Its successor was the even shorter-lived Creature Catalog of Dragon Magazine, which only saw six articles in total released over the course of Dragon's lifespan, covering D&D editions 1-3.
Index of Fiends
Because 1d4chan is awesome, we're gonna tell you what issues of White Dwarf had Fiend Factory articles in them, and what monsters were in each one.