William O'Leary, known as Arawata Bill, was born at Tuapeka, New Zealand, on 28 October 1865, the second child in a family of eight. His father, Timothy O'Leary, had emigrated from Prince Edward Island when gold was discovered in Otago in 1861; his mother, Mary O'Connor, came from County Clare, Ireland. They married in 1863. From Tuapeka, the family moved the short distance to Wetherstons near Lawrence. Judging from letters written in his adult life, and from family stories of the young O'Leary wagging school, his formal education was minimal.
O'Leary first worked on stations in Maniototo county, and in 1898 appeared in Queenstown and as a prospector in Martins Bay. He apparently prospected in South Westland for the next 14 years, before taking a job with the Westland County Council as ferryman on the Waiatoto River, earning the respect and affection of travellers and the local community.
He resigned as ferryman in 1928, and thereafter devoted most of his life to prospecting the river valley from which his nickname derived. It is possible that his long association with the Arawata stemmed from a practical joke. During an early prospecting expedition there, one of his companions pretended to find a nugget he had previously won on the Shotover. O'Leary refused to believe the nugget had been planted, and remained convinced that the Arawata carried heavy gold. He also searched for – and claimed to have found – a rumoured lost ruby mine in the Red Hills area, and kept a sharp eye out for a legendary South Westland treasure, a sea-boot filled with gold, allegedly hidden in the Cascade River valley.
William O'Leary was a consummate bushman, an utterly self-reliant man who thought nothing of crossing an alpine pass in thigh-boots, his pick doing duty as an ice-axe. His short, stocky frame was capable of carrying prodigious loads over terrain unsuited to his packhorse. Although perfectly content with his own company, he was by no means a hermit, and enjoyed meeting people, although he made a point of avoiding those he considered fools.
O'Leary retired to the Queenstown district in his mid 70s, still making occasional prospecting trips. In 1940, together with his younger brother, he visited the New Zealand Centennial Exhibition in Wellington; the electric light in his sister's Miramar home fascinated him.
Three years later O'Leary entered a Dunedin home for the aged, run by the Little Sisters of the Poor. The institutional life cramped him, and now elderly and confused, he made several attempts to return to the Arawata. He died in Dunedin Hospital on 8 November 1947 at the age of 82, having never married. He had made no significant gold finds during his lifetime, but, as he admitted to a friend, his prospecting only rationalised his love for the back country.
During his lifetime Arawata Bill was widely respected in South Westland for his bushcraft, his independence, and his integrity. After his death he became a minor legend, and in 1953 Denis Glover published a verse sequence, Arawata Bill, which presents him as an archetypal figure – prospector and solitary; but, at a deeper level, as representative of the endless human search for the unattainable. Two passes, in the Mt Aspiring National Park and west of Lake McKerrow, bear O'Leary's name.