Under-Dweller is the secondary antagonist as well as the first and only boss in the Nitrome game Cave Chaos 2. It is a pale purple, large lizard-like creature the size of the entire screen with tiny eyes and limbs that has two tongues in its mouth. It is not featured in the game's predecessor Cave Chaos.
The Under-Dweller appears in the fifteenth and final level of Cave Chaos 2. It acts in a fashion similar to the snow avalanche from another Nitrome game Avalanche, chasing after the player character which in this case is the miner. When it comes in contact with dynamite, it will freeze and shut its mouth for a few seconds.
When this happens, the miner gets a few seconds to move forward. Despite this, they can killed and eaten if they fall too much behind even if the Under-Dweller is paralyzed.
The Under-Dweller is beaten after it comes in contact with four dynamites and the miner reaches the final lantern at the end of the level. The subsequent cutscene shows miner as having made himself a new home from the Under-Dweller's skull and enjoying hot chocolate in moonlight after successfully escaping the creature.
- Oddly, Under-Dweller has a crest on its head. This might imply that the Under-Dweller is male, as it possibly uses the crest to attract a mate.