Boss Masks are vanity items dropped by bosses added by the Spirit Mod. They are worn in the social head slot, like vanilla masks. Each boss has a 1/7 (14.29%) chance to drop its own mask, with the exception of the Glade Wraith Mask, the Beholder Mask, and the R'lyehian Mask:
- The Glade Wraith Mask is acquired after completing the Adventurer's Sacred Vine quest.
- The Beholder Mask is acquired after completing the Adventurer's Beholder Slayer quest.
- The R'lyehian Mask has a 1/10 (10%) chance of being dropped by the R'lyehian.
- 184.108.40.206: Introduced Moon Jelly Wizard mask.
- 220.127.116.11: Introduced Glade Wraith, Beholder, and R'lyehian Masks.
- 18.104.22.168: Introduced.