A monster is defined as any creature that can be interacted with and potentially fought and killed. Even something as harmless as a frog or as benevolent as a unicorn is a monster by this definition. The term also applies to humans, elves, dwarves, and other civilized folk who might be friends or rivals to the player characters. Most of the monsters that haunt the D&D world, however, are threats that are meant to be stopped: rampaging demons, conniving devils, soul-sucking undead, summoned elementals- the list goes on.
This book contains ready-to-play, easy-to-run monsters of all levels, and for nearly every climate and terrain imaginable. Whether your adventure takes place in a swamp, a dungeon, or the outer planes of existence, there are creatures in this book to populate that environment.