|Variety|| (After dawn)|
|Spawn Time||Anytime, so long as Skeletron isn't killed|
|Summoned By||Entering the Dungeon before Skeletron is defeated|
Due to its unattainably high attack and defense, the Dungeon Guardian will always take 1 damage from all attacks (except criticals, which deal 2 damage) and will kill any players in one hit.
Before the Dungeon Guardian existed, Skeletron Heads fulfilled a similar role. Unlike with the Dungeon Guardian, killing all of the Skeletron Heads after they appear will grant the player access to the Dungeon as if they had killed Skeletron normally. The Dungeon Guardian was presumably introduced to counteract this unintended behavior.
- If the player is in an underground tunnel that is close enough to the dungeon (but not actually in the dungeon proper), the Dungeon Guardian may spawn anyway and kill them. The only way to avoid this would be to defeat Skeletron.
- Multiple Dungeon Guardians may spawn if the player ventures too far into the dungeon without killing Skeletron.
- The Dungeon Guardian has no death animation or sound, which indicates that it is not meant to be killed.
- It can also spawn directly on top of the player, though it is unknown if that's how fast they really move.
- Despite its sky-high attack and defense, it is actually possible to defeat this monster, though you must take special precautions to enter the dungeon in such a way that you can escape quickly after spawning it. In order to
- The easiest way to go about defeating it is by using a Minishark or Megashark (the difference is minimal due to the monster's defense) loaded with Crystal Bullets. Use any items that allow you to fly or move quickly (Wings, Gravitation Potions, Hermes Boots and Swiftness Potions on a Skybridge, etc.) and shoot at it, taking care to avoid direct contact with it. This will take a while, but there is no way around that.
- Added to the game.