This section includes new monsters and nonplayer characters introduced in Lost Laboratory of Kwalish, as well as stat blocks from the Monster Manual, Volo’s Guide to Monsters, and Mordenkainen’s Tome of Foes that are referenced in the adventure.
- Bandit Captain
- Berserker
- Bone Devil
- Brain in a Jar
- Clockwork Kraken
- Commoner
- Cultist
- Cult Fanatic
- Evoker
- Froghemoth
- Galeb Duhr
- Garret Levistusson
- Gelatinous Cube
- Gibbering Mouther
- Gynosphinx
- Kenku
- Martial Arts Adept
- Mary Greymalkin
- Medusa
- Merrenoloth
- Monodrone
- Mind Flayer Arcanist
- Ooze-Folk
- Quasit
- Quickling
- Skeleton
- Sprite
- Steam Mephit
- Stone Golem
- Stirge
- Swarm of Bats
- Thug
- Treant
- Umber Hulk
- Vampire
- Vampire Spawn
- Wraith
- The Wretched
- Xorn