William George Horner (9 June 1786 – 22 September 1837) was a British mathematician; he was a schoolmaster, headmaster and schoolkeeper, proficient in classics as well as mathematics, who wrote extensively on functional equations, number theory and approximation theory, but also on optics. His contribution to approximation theory is honoured in the designation Horner's method, in particular respect of a paper in Philosophical Transactions of the Royal Society of London for 1819. The modern invention of the zoetrope, under the name Daedaleum in 1834, has been attributed to him.
Horner died comparatively young, before the establishment of specialist, regular scientific periodicals. So, the way others have written about him has tended to diverge, sometimes markedly, from his own prolific, if dispersed, record of publications and the contemporary reception of them.
The eldest son of the Rev. William Horner, a Wesleyan minister, was born in Bristol. He was educated at Kingswood School, a Wesleyan foundation near Bristol, and at the age of sixteen became an assistant master there. In four years he rose to be headmaster (1806), but left in 1809, setting up his own school, The Classical Seminary, at Grosvenor Place, Bath, which he kept until he died there 22 September 1837. He and his wife Sarah (1787?–1864) had six daughters and two sons. One of the sons, another William Horner, continued to run the school. He, too, had a large family; the youngest were twins, Charles and Francis John Horner (1852–1887). Francis Horner matriculated at St. John's College, Cambridge in 1872, taking out a BA in 1876 and an MA in 1883. He became a lecturer in mathematics at the University in Sydney, where he died after only a few years - he had been advised to try a change of climate on account of tuberculosis.
A longer association with Australia comes through the issue of Horner's daughter Mary, which retained the name `Horner' through several generations. Mary's son Joseph Horner Fletcher, was a Methodist school headmaster in New Zealand and then Australia. Neville Horner Fletcher (1930- ), FTSE, FAA, is a physicist at the Australian National University.