Charles Gordon O'Neill (23 March 1828 – 8 November 1900) was a Scottish-Australasian civil engineer, inventor, parliamentarian and philanthropist, and a co-founder of the St Vincent de Paul Society in Australia and New Zealand.
He was born in Glasgow, son of John O'Neill, hotel proprietor, and his wife Mary. O'Neill studied civil engineering and mechanics at the University of Glasgow. He worked on the city's public works for 14 years, rising to become chief assistant in the Public Works Office. Although a full-time official he appears to have had permission to undertake private work for the Roman Catholic community, designing churches and schools. He served as a captain in the Third Lanarkshire Rifle Volunteers, and was active in the Society of St Vincent de Paul, becoming secretary at Dumbarton (1851), president of the Superior Council of Glasgow (1863), and a member of the Council General in Paris. He emigrated to New Zealand in 1864.
In January he became 1864 to the Otago provincial government and later district engineer at Clutha, where he laid out the town of Milton.
He arrived in Otago in January 1864, where he was a Member of Parliament for the Goldfields electorate in the Otago region (elected on 26 February 1866 during the 1866 general election; dissolution of the 4th New Zealand Parliament on 30 December 1870), and then for the Thames electorate (elected on 9 February 1871 during the 1871 general election; dissolution of the 5th New Zealand Parliament on 6 December 1875).