The Tasmanian masked owl (Tyto novaehollandiae castanops) is a bird in the barn owl family Tytonidae that is endemic to the island state of Tasmania, Australia. It is the largest subspecies of the Australian masked owl, the largest Tyto owl in the world, and is sometimes considered a full species. The subspecific name castanops, meaning "chestnut-faced", comes from the colouring of the facial disc. It was first described by John Gould (as Strix castanops), who wrote about it in his Handbook to the Birds of Australia as: