In a general sense, a vault dweller is any person who lives in one of the Vault-Tec vaults. When capitalized as a proper noun, the Vault Dweller is the player character in Fallout, most famous for defeating the Master and his super mutant army, helping Shady Sands grow into the New California Republic, founding the small village of Arroyo and fathering its elder (who too would bear a child; "the Chosen One").