Sir William Fletcher Barrett was born to English parents on February 10, 1844 in Jamaica. His family moved back to their native England in 1848 and in 1855 moved to Manchester where Barrett was educated at Old Trafford Grammar School. He subsequently took classes in chemistry and physics at the Royal College of Chemistry, London. In 1863 he became an assistant to John Tyndall at the Royal Institution, where he met and was influenced by Michael Faraday. He received a Master’s of Science from International College and became a lecturer in physics at the Royal School of Naval Architecture in 1869. From 1873 to 1910 he was a professor of physics at the Royal College of Science, Dublin.

He is best known for two lines of inquiry: his early work on ‘sensitive flames’ and his later studies on the electrical, magnetic, and thermal properties of iron and iron alloys. In 1899 he was elected a fellow of the Royal Society of London, in addition to already being a fellow of the Royal Society of Edinburgh and Royal Dublin Society. He was also knighted in 1912.

Barrett is remembered principally for his leadership in the founding of the Society of Psychical Research (SPR), an interest inspired by his experiences with mesmerism in the 1860s. In September 1876 he gave a paper before the anthropological section of the British Association for the Advancement of Science outlining some of his experiences. With spiritualist E. Dawson Rogers he founded the SPR in January of 1882.

He died suddenly of heart failure on May 26, 1925 at his home in London, England.