Hemideina crassidens, commonly known as the Wellington tree wētā, is a large, flightless, nocturnal insect in the family Anostostomatidae. This wētā species is endemic to New Zealand and populates regions in the southern half of North Island/Te Ika a Maui and the north-west of the South Island/Te Wai Pounamu. They forage arboreally during the night and are most likely polyphagous. There is obvious sexual dimorphism in adults. Individuals are reliant on tree cavities for refuge, social interactions and mating. The conservation status of H. crassidens is "not threatened".