Sir Rex de Charembac Nan Kivell CMG (8 April 1898 – 7 June 1977) was a New Zealand-born British art collector, who was knighted on the recommendation of the government of Australia, a country he never visited, for the gift and sale to the National Library of Australia of his collection of books, paintings, prints, documents, manuscripts and artefacts relating to the history of Australia, New Zealand and the Pacific. He has been described as "an archetypal outsider – illegitimate, homosexual, self-educated and antipodean".
Born as Reginald Nankivell in Christchurch, New Zealand to an unmarried mother, he was raised in the home of his maternal grandparents. He was educated at New Brighton Public School and the Royal College of Science.
As an under age youth and listing his profession as bookbinder, Reginald Nankivell enlisted with the New Zealand Expeditionary Force on 31 May 1916. He served in England (1916–1919) on the staff of No. 1 New Zealand Hospital General Hospital, Brockenhurst, Hampshire (part of his collection of photos was taken here) and at the New Zealand Command Depot, Codford, Wiltshire. On an extended period of leave in England, from October 1917 to May 1918, he began to pursue his growing antiquarian interests. Around 1918 he started to style himself Rex de Charembac Nan Kivell.
He attributed an early interest in collecting to Sydney Smith, an antiquarian book dealer in Christchurch whom Nan Kivell met while still at school. Nan Kivell was also inspired to read history and geography, especially works on European voyagers in the Pacific.
Nan Kivell worked on the La Tène archaeological excavations in Wiltshire, and presented the objects he unearthed to the Wiltshire Archaeological and Natural History Society Museum in Devizes.