Tainui is a tribal waka confederation of New Zealand Māori iwi. The Tainui confederation comprises four principal related Māori iwi of the central North Island of New Zealand: Hauraki, Ngāti Maniapoto, Ngāti Raukawa and Waikato.

The Tainui iwi share a common ancestry from Polynesian migrants who arrived in New Zealand on the Tainui waka, which voyaged across the Pacific Ocean from Hawaiki to Aotearoa (North Island) approximately 800 years ago. According to Pei Te Hurinui Jones, the Tainui historian, Tainui first entered the Waikato about 1400 bringing with them kumara plants.