William McMinn (1844 – 14 February 1884) was an Australian surveyor and architect, based in Adelaide.
He was born in Newry, County Down, Ireland, a son of Joseph McMinn and his wife Martha McMinn (née Hamill), who with their large family emigrated to Adelaide on the Albatross, arriving in September 1850.
After completing school, he was apprenticed to the architect James Macgeorge, but first practiced as a surveyor. He was involved in Boyle Travers Finniss's ill-fated 1865 expedition to Northern Australia surveying the area around the Adelaide River. Following the desertion of a majority of the party to Singapore, McMinn and 5 others purchased a 23-foot open boat which they named the Forlorn Hope and sailed it 2,000 miles (3,200 km) to Champion Bay, Geraldton, Western Australia. He was later involved in the 1872 surveying of the Overland Telegraph from Port Augusta to Darwin.
McMinn began practising as an architect in 1867, sometimes in partnership but usually independently. He designed many grand private residences, but also designed or assisted in the design of many of Adelaide's grand public buildings. Whilst in partnership with Edward John Woods, he designed the original Venetian Gothic building of the University of Adelaide, considered his greatest work.
William McMinn (1844–1884) married Mary Frances Muirhead (1853–1929) at Glenelg on 14 March 1877; they had two daughters:
- Mary Muirhead McMinn (1878–1957) married Charles Arthur Johns (1871–1956) in 1913
- Eileen Gordon McMinn (1879– ) married Rev. Harvey Langford Ebbs (1914–1987) on 31 August 1904
They had a home "Rutherdale" in Lower Mitcham.
One of his brothers, Gilbert Rotherdale McMinn (1841–1924), also worked as a surveyor on the Overland Telegraph Line, in February 1871 discovering Simpsons Gap, which proved a better route for the line. He served in various senior public service positions in the Northern Territory. McMinn Street, Darwin is named for him.
Three of his sisters, Sallie, Martha, and Elizabeth "Lizzie" McMinn (c. 1840– ) founded Tormore House School in North Adelaide around 1883 and retired to England in 1897.
The Mitchell Building at the University of Adelaide (1878)
The Governor's residence at Marble Hill (1878)
The Adelaide Children's Hospital (1878)
Mount Breckan mansion at Victor Harbor
- The Austral Hotel in Rundle Street
- Torrens Park (now Scotch College, Adelaide)
The main building at Prince Alfred College (1867)
The General Post Office (1867)
The Supreme Court of South Australia, alterations (1869)