Waitaha is a Māori iwi. Early inhabitants of the South Island of New Zealand, they were largely absorbed into the far larger Ngāi Tahu iwi during the 19th century via marriage and conquest, along with the Kāti Mamoe iwi.

The Waitaha have a long history, both verified and legendary. According to Waitaha custom, they pre-date the other mainland Māori iwi, having existed in what is now inland Canterbury and Otago for many years before the arrival in New Zealand of other Māori, and having previously also lived in other parts of the island chain such as Horowhenua. For this reason, some people of Waitaha descent view themselves as being separate from Māoridom as a whole, although there is little evidence to substantiate these legends. This has not stopped some from postulating on the Waitaha as a possible earlier wave of Polynesian settlement, although these theories are not widely accepted.

The Whanau Show