Born in 1575 in the Southwark section of the City of London, Thomas was the son of Richard Garnet, a Confessor of the Faith, and nephew of the famous Jesuit missionary and martyr, Father Henry Garnet.
In his youth, he was a page to the Count of Arundel. At sixteen, he entered the College of St. Omer in the Low Countries and, two years later, was sent to Spain. He continued his studies at the College of St. Alban in Valladolid and was ordained to the priesthood in 1599. After his ordination, he returned to England and, under the alias of Thomas Rokewood, spent nearly six years wandering up and down the country ministering to the faithful and bringing souls back to the Catholic Faith.
About 1605, Thomas was arrested and falsely accused of participating in the Gunpowder Plot, the failed plan to assassinate James I. He was tortured for information, the authorities hoping to extract information about his famous uncle, Father Henry Garnet, Superior of the English Jesuits, who was implicated in the Plot because he refused to break the Seal of Confession.
After roughly nine months, he was released and deported to Flanders. There he entered the Jesuit Order, and just a year after his deportation, he returned to England. He was arrested after refusing to swear allegiance to the monarch as head of the Church of England, known as The Oath of Supremacy. He was hanged at Tyburn in 1608 as a traitor to the crown.
“I wandered,” he said during his trial, “from place to place to recover souls which had gone astray and were in error as to the knowledge of the true Catholic Church.”
Before he died, he publicly reaffirmed himself as a Jesuit and a priest. He was canonized in 1970 and is included among the Forty Martyrs of England and Wales.