Thomas Rangiwāhia Ellison, also known as Tom or Tāmati Erihana, was born at Ōtākou, on the Otago Peninsula, sometime between 1866 and 1868. Ellison's mother, Nani Weller (Hana Wēra), was the only child of Edward Weller, who had established the Ōtākou whaling station in 1831, and Nīkuru, the daughter of Te Mātenga Taiaroa and Hine-i-whāriua of Ngāi Tahu and Ngāti Mamoe. His father, Rāniera Tāheke Ellison, was the son of Thomas Ellison and Te Ikairaua (Te Ikaraua) of Ngāti Moehau, a hapū of Te Āti Awa. Tom Ellison, the third of twelve children, was given the middle name of Rangiwāhia after his great-uncle, a noted Taranaki warrior.
Rāniera Ellison had come to Otago in search of gold. In 1862 he and two companions, Hākaraia and Hēnare Patukopa, discovered gold at what is now Māori Point on the Shotover River. They were said to have taken at least 300 ounces in one day. In 1882 Rāniera became converted to the cause of the exiled Parihaka leaders Te Whiti and Tohu, when they visited the Kaik, Ōtākou. He provided food for their followers who were imprisoned in Dunedin, and interceded with the authorities to allow them to hold their monthly ceremonies. He later made numerous trips to Parihaka, and gave financial assistance to help rebuild the settlement.
Although Tom Ellison was to inherit his father's concern with Māori grievances, he was better known as a rugby player. About 1881 he was introduced to rugby football by his cousins at the Kaik. Jack Taiaroa was to become a prominent member of the first New Zealand rugby team in 1884, and Riki Taiaroa later joined Ellison in the touring Native team of 1888–89. In 1882 Ellison, having won the Makarini scholarship, was sent to Te Aute College, Hawke's Bay, where he played for the senior team in 1883 and 1884. He joined the Pōneke Football Club, Wellington, in 1885 and was a provincial representative from 1885 to 1889 and in 1891 and 1892. His first international honours came with the New Zealand Native Football Team, a professional side, which toured Great Britain and Australia in 1888–89. It was a hard tour with 107 matches in 54 weeks, 16 of which were spent travelling. Ellison scored 113 points, including 43 tries, on the tour – the second-highest tally.
Initially a forward and later a wing, Ellison played half-back for Pōneke in 1891, and from that experience developed the wing-forward position to block interference with passing from the base of the scrum. The system was quickly adopted by Wellington and then throughout New Zealand; it was superseded by the eight-man scrum in 1932.
In 1893 Ellison captained the first official New Zealand team. Before it toured Australia he proposed to the first annual general meeting of the New Zealand Rugby Football Union that the uniform be a black jersey with silver fern monogram, black cap and stockings and white knickerbockers. This was similar to the old Native team uniform, and with a switch to black shorts in 1901 it became the familiar All Black uniform.
Ellison, in 1898, was one of the first players to call for players on tour to be paid the equivalent of their normal wages. In 1902 he published The art of rugby football, an early rugby coaching manual. It also includes comments on teams and tours with which he was involved. Ellison's career record was 117 (68 first-class) matches in which he scored 160 points, including 51 tries.
Tom Ellison took a keen interest in Ngāi Tahu land claims: he was appointed an interpreter in the Native Land Court in 1886, and stood three times, unsuccessfully, for the Southern Māori seat in Parliament. From 1891 he worked as a solicitor. In 1902, as a barrister in the Wellington law firm Brandon, Hislop and Johnston, he was admitted to the Bar, one of the first Māori to attain that distinction. He became a familiar figure commuting to work from Eastbourne in one of the first motor cars seen in Wellington.
On 22 March 1899 Tom Ellison married Ethel May Howell in Wellington. She was a daughter of the Riverton whaler and pastoralist John Howell and his second wife, Caroline Brown, of Ngāi Tahu and Ngāti Mamoe. They had three children, two of whom died in infancy; Hinemura, born in 1900, died in 1989. While the family house at Muritai hill was being built Tom Ellison was hospitalised at Porirua Lunatic Asylum, where he died on 2 October 1904 in his late 30s. Ellison was to have been buried at Karori, but the body was intercepted at Porirua railway station by Māori representing his parents. With the agreement of Ethel Ellison and the Public Trustee, he was taken south and buried at Ōtākou. Ethel Ellison married Percy Braithwaite in 1906.