Francis Tresham (c. 1567 – 23 December 1605) was a member of the group of English provincial Catholics who planned the failed Gunpowder Plot of 1605, a conspiracy to assassinate King James I of England.

An anonymous letter delivered to one of them, William Parker, 4th Baron Monteagle, found its way to the English Secretary of State, Robert Cecil, an event which eventually proved decisive in the conspiracy's failure.

[1] According to the antiquary Anthony Wood, Tresham was educated in Oxford at either St John's College or Gloucester Hall or both,[2] although biographer Mark Nicholls mentions that there appears to be no other evidence to corroborate that claim.

He proclaimed the accession of James I to the English throne, but the king's promises to Thomas of forestry commissions and an end to recusancy fines were not kept.

"[7] Authors Peter Marshall and Geoffrey Scott describe him as possessing a "somewhat hot-headed nature",[8] while another source calls him a "wild unstayed man".

[10] Essex's aim was to secure his own ambitions, but the Jesuit Henry Garnet described the young men who accompanied him as being interested mostly in furthering the Catholic cause.

[12] The identity of these individuals is unclear, but Tresham was promised freedom on the condition that over the next three months his father pay £2,100 to William Ayloffe, to "save his lyef attainder in bloode.

The experience did not dissuade him from engaging in further conspiracies; in 1602 and 1603 he was involved in the missions to Catholic Spain made by Thomas Wintour, Anthony Dutton (possibly an alias of Christopher Wright)[13] and Guy Fawkes, later dubbed by the English government as the Spanish Treason.

[1][14] However, upon James's accession to the throne, he told Thomas Wintour (secretary to Tresham's brother-in-law William Parker, 4th Baron Monteagle), that he would "stand wholly for the King", and "to have no speech with him of Spain.

He hoped to achieve this by blowing up the House of Lords with gunpowder and inciting a popular revolt to install James's daughter Princess Elizabeth as titular Queen.

[19][nb 1] Despite their shared upbringing and involvement in the Spanish Treason, the conspirators chose not to reveal the plot to him until 14 October 1605, shortly after his father died, and just weeks before the planned explosion.

Tresham had no money to spare, his father's debts having reduced his inheritance,[20] although he paid a small sum[nb 2] to Thomas Wintour, on the understanding that the latter was to travel to the Low Countries.

Therefore I would advise you, as you tender your life, to devise some excuse to shift your attendance at this parliament; for God and man hath concurred to punish the wickedness of this time.

Mark Nicholls states that he almost certainly wrote it, pointing to the fact that once Catesby was made aware of its existence he immediately suspected Tresham and went with Thomas Wintour to confront him.

[1] The two threatened to "hang him", but "with such oaths and emphatic assertions" Tresham managed to convince the pair of his innocence, the next day urging them by letter to abandon the plot.

[28] Author Alan Haynes views Tresham as the most likely culprit, but raises the possibility that Cecil penned the letter himself, to protect a source.

[30] When Monteagle's letter was shown to the king on Friday 1 November, James felt that it hinted at "some stratagem of fire and powder",[31] perhaps an explosion exceeding in violence the one that killed his father, Lord Darnley, in 1567.

Fellow plotter Thomas Percy said he was ready to "abide the uttermost trial",[34] and subsequently on 4 November Catesby and several others left London for the Midlands to prepare for the planned uprising.

During his last days, he was attended by three more doctors and a nurse, along with William Vavasour, a rumoured illegitimate child of Thomas Tresham and possibly Francis's half-brother.

Tresham apologised to the Jesuit priest Henry Garnet for implicating him in the Spanish Treason, and used the rest of his deathbed confession to protest his innocence.