Creatures that can be made to spawn on player-made artificial biomes anywhere or by Mob Spawners placed underground are not included.
Nearly all naturally appearing Underground Creatures are aggressive towards player characters (except for time-limited Ghost Creatures and all Creatures on gameworlds with the "Pro" option "peaceful creatures" enabled), and the deeper their natural habitat, the stronger and tougher they tend to be.
Most of these Creatures can also be made to spawn on player-made artificial biomes/arenas on the surface, as long as these biomes are made from rocks that are typical for the listed underground layers. Even several types of Ore Nodes or liquids like liquid Lava can make specific Underground Creatures spawn on or nearby them.
Please note that not all Underground Creatures are Sunlight Intolerant. Warmworms and all Corrupted Creatures can prevail in sunlight, and most Underground Creatures will also spawn during day and night.
Pages in category "Underground Creatures"
The following 17 pages are in this category, out of 17 total.