Henry Matthew Stowell was born at Waimate North, Bay of Islands, according to his own account on 4 February 1859, the son of John Shephard Stowell, a sawyer who had come to New Zealand from the United States, and his wife, Hūhana (Susan), daughter of Rīmaumau (Maumau), a high-born woman of Ngāpuhi. Attending school first at Parnell in Auckland, Stowell, apparently at the instigation of Governor George Grey, continued his education at the Wesleyan Native Institution, Three Kings, where he excelled as a scholar and athlete. He subsequently worked with a survey party in Northland, but the most important experience of his teens, and in some sense of his whole life, was a period of more than a year at Waitaha village, near Ahipara, absorbing Māori lore from the tohunga Ngā Kuku Mumu, whom he later described as 'my first and my grandest old mentor'. Stowell's abiding interest thereafter was the acquisition of traditional Māori knowledge, especially mythology, genealogy and cosmology.
Stowell spent some time as a sawyer in the Mangakāhia district. A relationship with Ellen, the wife of his brother Samuel, resulted in the birth of a son, Hector Arthur Ngāpua Stowell, in Auckland in November 1886. Henry went to live at Waiwhetū, in the Hutt Valley, and found his métier in his bilingual expertise when in 1888 he was authorised to act as an interpreter in the Native Land Court. On a visit to Taranaki he met Mary Rachel Robson, the daughter of James Robson, a sawmiller, and Mere Ngāmai, also known as Mary Harrison, a close relation of Te Wharepōuri of Te Āti Awa descent; they were married on 27 July 1891 at Ngaere, near Stratford. In the 1890s and early 1900s the family (there were eventually seven children) lived at Hāwera, although Stowell himself often travelled widely in the course of both business and collecting information from learned Māori. Assuming the name Hare Hongi as a tribute to his Ngāpuhi ancestors, he published articles and some highly rhetorical verse, so impressing members of the government with his erudition that he was given official encouragement to gather Māori lore and legends. In 1908 Stowell was appointed a temporary clerk and interpreter in the Native Department in Wellington, a position which was made permanent in 1913. He was particularly proud of his role as interpreter and prosecution witness (on a disputed point of Māori language usage) in the trial of Rua Kēnana at Auckland in 1916.
Ngā Kuku Mumu had forbidden Stowell to write down what he was told since it was sacred. Nevertheless, Stowell believed he had a duty to correct what he considered erroneous views, and many of his articles, in the Journal of the Polynesian Society between 1893 and 1923 and in newspapers, were critical of the construction of Polynesian history, including the arrival of a fleet in New Zealand about 1350, promulgated by S. Percy Smith and other Pākehā scholars: 'All of that stuff is spurious'. He did not exempt from his trenchant criticism the works of James Cowan, the journalist and author who in 1913 married Eileen, the eldest of Stowell's six daughters. Kupe was, in Stowell's view, not a navigator but a mythical 'volcanic deity'; Māori had been in New Zealand for thousands of years; and New Zealand was but a remnant of a continental Hawaiki once extending beyond the equator. These views were not widely accepted.
After his resignation from the Native Department in May 1921, Stowell continued to earn a living as an interpreter, and offered lessons in Māori to interested Pākehā. He recommended his own work, the Māori–English tutor and vade mecum, published in 1913, as a textbook. His most notable pupil was Lady Alice Fergusson, wife of the governor general of the late 1920s. He gave lectures on Māori lore, made radio broadcasts on the meaning and pronunciation of Māori placenames, and wrote articles on placenames for a motoring magazine. Stowell submitted several waiata to Apirana Ngata for inclusion in Ngā moteatea. Ngata made no use of these but some of Stowell's pieces eventually appeared in the third and fourth volumes.
Increasingly in the 1920s and 1930s Stowell became a picturesque character around Wellington. Tall, bearded, with a shock of white hair and blue eyes, pipe in mouth, ever-present scarf flicking about in Wellington's stiffer breezes, he was instantly recognisable. His behaviour likewise attracted attention: he was gregarious, convivial (although always courteous), often gleefully theatrical as he recounted at length in clubs and pubs his life experiences. But his intellect remained acute: in 1939, at the age of 80, he assisted researchers for the projected centennial historical atlas with details of Northland tribal locations and affiliations. Henry and Rachel Stowell seem to have lived apart for some years before her death at New Plymouth in 1939. In later life, Henry maintained close relationships with a number of women. He died at Wellington on 23 March 1944.
A licensed Māori-language interpreter, Henry Stowell was an interpreter in a more general sense, one of many nineteenth-century New Zealanders who were genuinely bicultural and who moved easily between and within Māori and Pākehā communities. On one occasion at Ōrākei, Auckland, playing his violin to lead a local Māori choir in the tune 'Little brown jug', he was delighted at the inadvertent 'Māorification' of the air into a new waiata poi. It is an incident which, although trivial, perhaps signifies the role people like himself played as brokers of cultural values.