The Monster Manual is the primary bestiary sourcebook for monsters in the Dungeons & Dragons fantasy role-playing game, first published in 1977 by TSR. The Monster Manual was the first hardcover D&D book and includes monsters derived from mythology and folklore, as well as creatures created specifically for D&D. Creature descriptions include game-specific statistics, a brief description of its habits and habitats, and typically an image of the creature. Along with the Player's Handbook and Dungeon Master's Guide, the Monster Manual is one of the three "core rulebooks" in most editions of the D&D game. As such, new editions of the Monster Manual have been released for each edition of D&D. Due to the level of detail and illustration included in the 1977 release, the book was cited as a pivotal example of a new style of wargame books. Future editions would draw on various sources and act as a compendium of published monsters.

Dungeons & Dragons is a fantasy tabletop role-playing game (RPG) originally created and designed by Gary Gygax and Dave Arneson. The game was first published in 1974 by Tactical Studies Rules, Inc. (TSR). It has been published by Wizards of the Coast, later a subsidiary of Hasbro, since 1997. The game was derived from miniature wargames, with a variation of the 1971 game Chainmail serving as the initial rule system. D&D's publication is commonly recognized as the beginning of modern role-playing games and the role-playing game industry, and also deeply influenced video games, especially the role-playing video game genre.