John Hamilton Pagan, Scottish minister and plant collector, was the son of John Pagan, Doctor of Divinity and amateur botanist. He studied at the University of Glasgow and qualified as Master of Arts (MA) in 1891 and Bachelor of Divinity (BD) in 1894. He came to South Africa in or before 1901, for in that year he requested the authorities of the Orange River Colony (now the Free State) to appoint him as a marriage officer. By 1908 he was a minister in the Presbyterian Church in South Africa and resided in Kimberley. Just before his death he wrote The flower of the hidden crown, and other letters to boys and girls from a South African stoep (Edinburgh, 1913; 4th ed., 1922), a collection of letters originally published in the Presbyterian Churchman.
In 1910 Pagan collected, dried and named a number of plants at Klein Boetsap (west of Warrenton, in the Northern Cape) for the McGregor Museum in Kimberley. Two years later he presented the museum with a large number of mounted and named plants from De Aar.