Octavius Hadfield (born 6 October 1814 at Bonchurch, Isle of Wight, United Kingdom - died 11 December 1904 at Edale, near Marton, Manawatu, New Zealand) was Archdeacon of Kapiti, Bishop of Wellington from 1870 to 1893 and Primate of New Zealand from 1890 to 1893.
He was born into an affluent family but often had very poor health and nearly died on several occasions. He received an excellent university education but did not finish his degree due to ill health. As a member of a wealthy family he was able to tour though Europe. Normally, lack of a degree would have prevented him being ordained but he was able to secure a position in New Zealand. A member of the Church Missionary Society for thirty years, he was recognised as an authority on Māori customs and language. His views on Māori rights, expressed in several books strongly criticised the actions of the New Zealand Government. Hadfield married Catherine (Kate) Williams (24 February 1831 – 8 January 1902) a daughter of the Rev. Henry Williams and Marianne Williams.
During his early years he travelled throughout the Wellington region that had been conquered by numerous Taranaki tribes. He became close friends with the Ngati Toa warlord Te Rauparaha who had led the invasion of the wider Wellington region during the long running musket wars. It was Te Rauparaha's Christian son Tāmihana who had invited him to the Māori community to live. Hadfield buried the old cannibal in 1849 after his release from imprisonment.
He was considered conservative and evangelical in his religious beliefs and rejected Darwinianism. He was very friendly with Samuel Marsden but did not share his views on high church Anglicanism.
He became part of the Otaki Ngati Raukawa community where he made every effort to learn Māori language and customs and shared these with governor George Grey. They went to the same church. He lived in the community for 30 years, established 20 mission schools and became well integrated into the Māori community. In 1852 he published a spelling book for Māori children. Later he became increasingly intolerant and dogmatic in his views as he clashed with the government. He lived in an age when the early influence of missionaries had declined. 
After arriving in New Zealand in January 1839, Hadfield was stationed at Paihia in the Bay of Islands. Following a request by Tāmihana Te Rauparaha and Mātene Te Whiwhi for a missionary in their area, Hadfield travelled with Henry Williams to establish an Anglican mission on the Kapiti Coast in November 1839. In December 1843 Bishop Selwyn, the first Anglican Bishop of New Zealand, attended Otaki to confirm a young chief and 142 of his followers.
Relations between Māori and Pākehā
Following the Wairau Affray in 1843, where a confrontation between Te Rauparaha and group of settlers left twenty-two Europeans dead, many settlers believed an attack on then thinly populated Wellington was possible and Hadfield was seen as a peacemaker preventing the spread of hostilities. Hadfield became far less popular when in 1860, Hadfield upheld Wiremu Kīngi's claim to the Waitara block. The surveying of this land prior to military occupation precipitated the First Taranaki War, and Hadfield became a leading critic of the Government in these actions. He "was for some time the most unpopular man in the colony". He was described in the press at the time as "a traitor and a bigotted meddlesome missionary" .
In 1877 Wiremu Parata took Hadfield and the Church to court over a gift of land which was not used for a school as intended; the far-reaching case Wi Parata v the Bishop of Wellington was lost when the Treaty of Waitangi was ruled a simple nullity.
- "Blain Biographical Directory of Anglican clergy in the South Pacific" (PDF). 2015. Retrieved 12 December 2015.
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- "The Church Missionary Gleaner, March 1842". Remarkable Introduction and Rapid Extension of the Gospel in the Neighbourhood of Cook's Straits. Adam Matthew Digital. Retrieved 10 October 2015. (subscription required (. ))
- "The Church Missionary Gleaner, January 1860". Otaki, New Zealand. Adam Matthew Digital. Retrieved 24 October 2015. (subscription required (. ))
- Starke, June. "Octavius Hadfield". Te Ara. Retrieved 7 October 2013.
- Octavius Hadfield , Anglican Church of Aotearoa. www.anglican.org.nz/content/download/539/4101. 1112. rtf