Dungeon Guardian

The Dungeon Guardian guards the Dungeon against intruders. If a player tries to break into the Dungeon without killing Skeletron, this enemy will appear and attack. If hit, the Dungeon Guardian's massive damage will slay any player instantly. Deep caves and Corruption chasms near the Dungeon should be avoided until Skeletron is slain, as merely being close to the Dungeon at a certain depth is considered a break-in.

Dungeon Guardians are immune to the Poisoned and the On Fire! debuffs.