Fiend Folio is the name of three separate products published for successive editions of the fantasy role-playing game Dungeons & Dragons (D&D). All three are collections of monsters.

The drow or dark elves are a dark-skinned and white-haired subrace of elves connected to the subterranean Underdark in the Dungeons & Dragons fantasy roleplaying game. The drow have traditionally been portrayed as generally evil and connected to the evil spider goddess Lolth. However, later editions of Dungeons & Dragons have moved away from this portrayal and preassigned alignment. More recent publications have explored drow societies unconnected to Lolth.