Thomas Percy was born in 1560. He was a wild and belligerent character, who was briefly jailed for killing a Scotsman in a brawl in 1596. A Catholic convert, his marriage to Martha Wright, the sister of fellow conspirators Christopher and John Wright, had something to do with his conversion.
Percy came from a great aristocratic family. His great-grandfather had been the fourth Earl of Northumberland and he was trusted and employed by his cousin, the ninth Earl.
The Earl even used him in political missions, such as discussions with King James on the future of Catholics in England. The Earl was appointed captain of the King's bodyguard early in the new reign and made Percy one of their number.
As well as being related to the Wright brothers, Percy was a friend of Catesby. He was said to have been frustrated by the King's failure to carry out a promise of leniency towards Catholics and was initiated into Catesby's plot in May 1604.
Percy rented the house next to the House of Lords from Henry Ferrers. In 1605 he rented the basement under the House of Lords.
Percy dined with Northumberland on the evening of 4 November, to try to find out whether the plot had been discovered. Because Percy had rented the property in which Guy Fawkes was found, he was easily identified as one of the conspirators.
He was found at Holbeach House in Staffordshire with the other conspirators, and killed in the shoot-out on 8 November. His head was cut off and, like Catesby's, was stuck on the roof of the House of Commons.