Ralph Allen (1693 – 29 June 1764) was an entrepreneur and philanthropist, and was notable for his reforms to the UK postal system. He was baptised at St Columb Major, Cornwall on 24 July 1693. As a teenager he worked at the Post Office. He moved in 1710 to Bath, where he became a post office clerk, and at the age of 19, in 1712, became the Postmaster of Bath. In 1742 was elected Mayor of Bath, was the Member of Parliament for Bath between 1757 and 1764.
Henry Jenner FSA (1848-1934) was a British scholar of the Celtic languages, a Cornish cultural activist, and the chief originator of the Cornish language revival. Jenner was born at St Columb Major on 8 August 1848. He was the son of Henry Lascelles Jenner, who was one of two curates to the Rector of St. Columb Major, and later consecrated though not enthroned as the first Bishop of Dunedin and the grandson of Herbert Jenner-Fust.
John ("Jack") Frederick Crapp (14 October 1912 - 13 February 1981) was an English cricketer who played first-class cricket for Gloucestershire County Cricket Club between 1936 and 1956, and played in the English cricket team on tour in the winter of 1948-49. He was born in St Columb Major, Cornwall, and died in Knowle in Bristol. He began his career with Stapleton Cricket Club in Bristol, scoring a 'duck' for the third team on his debut.
Richard "Dick" Bullock (August 20, 1847 near St Columb Major, Cornwall – 1921) was a Cornishman who once sang in a Methodist choir and later became a legendary figure of the Wild West Cowboy era. His quick-shooting deeds working on the Deadwood stage gained him the nickname "Deadwood Dick". Early in life his family moved to nearby hamlet of Retew where his father, Captain John Bullock, became the manager of a local clay-works.
John Trehenban (pronounced TREM-on) (1650–1671), of St Columb Major in Cornwall, United Kingdom, was a murderer sentenced to imprisonment in a cage on Castle An Dinas downs and starved to death. The murder of the two young girls is recorded in the Parish Register.
Stephen Robert Nockolds, FRS (10 May 1909-7 Feb 1990) was a geochemist, petrologist and winner of the Murchison Medal of the Geological Society of London. Robert Nockolds was born at St Columb Major, Cornwall, the son of Dr Stephen Nockolds, a surgeon of Brighton, and his wife Hilda Tomlinson. He was educated at Ascham St Vincent's School, Eastbourne and at Felsted School where his interest in rocks already manifested itself.
John King (died 30 March 1621) was a Church of England clergyman and bishop of London from 1611–1621. John King was educated at Westminster School and Christ Church, Oxford. A chaplain to bishop John Piers, King became preacher to the city of York before becoming domestic chaplain to Thomas Egerton in London. As Rector of St Andrews, Holborn in 1597 and prebend of Sneating in St Paul's in 1599, King became a well-known Calvinist anti-Catholic preacher.
Robert Hoblyn MP FRS (1710–1756) was an English politician and book collector. Hoblyn was born at Nanswhyden House, and baptised at St. Columb Major in Cornwall 5 May 1710. His father, Francis Hoblyn, born in 1687, a J.P. for Cornwall and a member of the Stannary parliament, was buried at St. Columb on 9 Nov. 1711. His mother was Penelope, daughter of Colonel Sidney Godolphin of Shropshire. She married secondly, on 5 Sept. 1714, Sir William Pendarves of Pendarves.
Arthur Ivan Rabey was best known as a Cornish historian and author from St Columb Major in Cornwall. He was also a journalist, broadcaster and local politician. In 1974 he was created a bard of The Cornish Gorseth and took the bardic name "Gwas Colum" meaning servant of St Columb. He died on 21 January 2008, aged 76, following a long illness.
Richard Parkyn was a champion Cornish wrestler. He was born at Parkyn's Shop which lies at three parish boundaries, St Columb Major, St Columb Minor and St Mawgan. There was a saying at the time that Parkyn was "So great that all three parishes claimed him". He was also known as The Great Parkyn. Little is recorded about his life other than newspaper reports of his fights.