Ngāti Toa, Ngāti Toarangatira or Ngāti Toa Rangatira, is a Māori iwi (tribe) based in the southern North Island and in the northern South Island of New Zealand. Its rohe (tribal area) extends from Whanganui in the north, Palmerston North in the east, and Kaikoura and Hokitika in the south. Ngāti Toa remains a small iwi with a population of only about 4500 (NZ Census 2001). It has four marae: Takapūwāhia and Hongoeka in Porirua City, and Whakatū and Wairau in the north of the South Island. Ngāti Toa's governing body has the name Te Rūnanga o Toa Rangatira.

The iwi traces its descent from the eponymous ancestor Toarangatira. Prior to the 1820s, Ngāti Toa lived on the coastal west Waikato region until forced out by conflict with other Tainui iwi headed by Pōtatau Te Wherowhero (c. 1785 - 1860), who later became the first Māori King (r. 1858–1860). Ngāti Toa, Ngāti Rārua and Ngāti Koata, led by Te Rauparaha (c. 1765-1849), escaped south and invaded Taranaki and the Wellington regions together with three North Taranaki iwi, Te Āti Awa, Ngāti Tama and Ngāti Mutunga. Together they fought with and conquered the turangawaewae of Wellington, Ngāti Ira, wiping out their existence as an independent iwi. After the 1820s, the region conquered by Ngāti Toa extended from Miria-te-kakara at Rangitikei to Wellington, and across Cook Strait to Wairau and Nelson.