Thomas Garnet, SJ (9 November 1575 – 23 June 1608) was a Jesuit priest who was executed in London during the English Reformation.

Richard Garnet, Thomas's father, was at Balliol College, Oxford, at the time when great severity began to be used against Catholics.

[1] His example provided leadership to a generation of Oxford men which was to produce Edmund Campion, Robert Persons,[1] and other English Catholics.

Thomas attended Collyer's School in Horsham, Sussex, and was afterwards a page to one of the half-brothers of Philip Howard, Earl of Arundel, who were, however, conformists (i.e. conformed to the Anglican faith).Because English colleges had been turned over to Protestants, English Catholics had an incentive to go to the continent for their education.

[1] They were lucky in finding as a travelling companion a Jesuit Father William Baldwin, who was going to Spain in disguise under the alias Ottavio Fuscinelli, but misfortunes soon began.

After severe weather in the English Channel, they found themselves obliged to run for shelter to The Downs, where their vessel was searched by men from some of Queen Elizabeth's ships, and they were discovered hiding in the hold.

Though no connection with the conspiracy could be proved against Thomas, he was kept in the Tower of London for seven months, at the end of which time he was suddenly put on board ship with forty-six other priests, and a royal proclamation, dated 10 July 1606, was read to them, threatening death if they returned.

Garnet was offered his life if he would take the oath, but he steadfastly refused, and was executed at Tyburn at the age of 32, protesting that he was "the happiest man this day alive".

[1] St. Thomas Garnet's Independent School in Boscombe, Bournemouth, which closed in 2020, was dedicated to the saint at its foundation.