Jesuit priest and martyr. Born in Southwark, Garnet was educated at Horsham grammar school. His father was imprisoned for his religious beliefs and his uncle was the more famous Henry Garnet, S.J., who was prominent in organizing and deploying the English Catholic clergy and who died on the scaffold in 1606 for alleged complicity in the Gunpowder Plot. Thomas Garnet became Lord William Howard's page and entered the Jesuit College at St Omer, whence he moved to the English College at Valladolid in 1596, where he was ordained priest in 1599. After a short spell of work as a priest in England he became a Jesuit in 1604. After the discovery of the Gunpowder Plot he was arrested, imprisoned, and rigorously examined about his own and his uncle's supposed involvement; when he proved his innocence he was banished with other priests in 1606.
After his novitiate in Louvain, he returned in defiance of the law in 1607. A few weeks later he was arrested and again imprisoned, this time in the Gatehouse and at Newgate. He was tried at the Old Bailey, condemned to death for being a priest ordained overseas who had returned to England, and was executed at Tyburn on 23 June. He is the protomartyr of the College of St Omer (now at Stonyhurst, Lancs.). He was canonized by Paul VI in 1970 as one of the Forty Martyrs of England and Wales. Feast: 25 October.
H. Foley, Records of the English Province of the Society of Jesus (1877–82), ii (2), 475–505;J. H. Pollen, Acts of the English Martyrs (1891);R. Challoner, Memoirs of Missionary Priests (ed. J. H. Pollen, 1924).