- For the mask obtained from the Clothier, see Mime Mask.
- For defensive headpieces, see Armor.
Boss Masks are vanity items dropped by all non-event bosses, and also from the Old One's Army bosses. They are worn in the social head slot. Each boss has a 14.29% chance to drop its own mask.
- The Ancient Cultist Mask is arguably the most difficult to obtain, not because it is hard to defeat the Lunatic Cultist, but because it is impossible to farm him without spawning in the Lunar Events. The Events must be completed in order for the Cultists outside of the Dungeon to spawn, which must be killed in order for the Lunatic Cultist to be spawned again. Doing all of it may take a long time, which may make the Mask not worth it.
- The Ocram Mask is now unobtainable, however any Ocram Mask already existing in Character inventories or Worlds is still usable.
- Two of the masks have animations. The King Slime and Moon Lord Masks will move around when the player moves left or right.
- Desktop 1.2.3: Added Brain of Cthulhu, Wall of Flesh, Twins, Skeletron Prime, Queen Bee, Plantera, Golem, Eater of Worlds, Eye of Cthulhu, and Destroyer Masks.
- Console 1.07: Added all Masks up to Desktop 1.2.4 except for the Duke Fishron Mask.
- 3DS-Release: Introduced all Masks up to Desktop 1.2.4, but with a low drop rate.