Ambrose Rookwood (c. 1578 – 31 January 1606) was a member of the failed 1605 Gunpowder Plot, a conspiracy to replace the Protestant King James I with a Catholic sovereign.

He was enlisted into the plot in September 1605 by Robert Catesby, a religious zealot whose impatience with James' treatment of English Catholics had grown so severe that he conspired to blow up the House of Lords with gunpowder, killing the king and much of the Protestant hierarchy.

With the other conspirators he had recruited, Catesby also planned to incite a rebellion in the Midlands, during which James's nine-year-old daughter Princess Elizabeth would be captured, and installed as titular queen.

The explosion was planned to coincide with the State Opening of Parliament on 5 November 1605, but the man left in charge of the gunpowder stored beneath the House of Lords, Guy Fawkes, was discovered there and arrested.

Ambrose's Papist cousin Edward had spent ten years in prison for his faith, but in 1578 he entertained Queen Elizabeth I at his home, Euston Hall.

He was apparently happy to advertise his faith; in the summer of 1605 he commissioned a London cutler, John Craddock, to place a Spanish blade into a sword hilt engraved with the story of the Passion of Christ.

The Tyrwhitts were another prominent Roman Catholic family and his wife was possibly a first cousin to his future fellow conspirator Robert Keyes.

[14][15] He therefore planned to kill the king by blowing up the House of Lords with gunpowder, and then inciting a popular revolt to install James's daughter, Elizabeth, as titular queen.

[17] He had been asked to supply them with gunpowder about a year earlier, under the pretence that it was for William Stanley's regiment in Flanders—no longer an illegal operation due to the recent Treaty of London[10]—but otherwise provided no funds for the conspiracy.

[3] He was at first concerned for the welfare of the Catholic lords who would be present at the explosion, but his compunction was alleviated when Catesby promised him that they would be tricked out of attending Parliament that day.

[6] Rookwood had stayed with the Wintours at Huddington Court, and that month with the Catholic Lacons at Kinlet Hall,[13][18] but at Cateby's behest he rented Clopton House near Stratford upon Avon, and moved there after Michaelmas.

[20] A few days before the planned explosion he changed his mind about the sword he had ordered John Craddock to make, and had the cutler replace the grip with a gold one.

[4][21] The existence of the plot had been revealed in an anonymous letter delivered ten days earlier to William Parker, 4th Baron Monteagle, warning him to keep away from Parliament.

On the evening of 4 November the authorities made a search of the House of Lords, where they discovered one of the plotters, Guy Fawkes, guarding a hoard of explosives.

News of Fawkes's capture soon spread through London, prompting Christopher Wright (brother of John) to rush to Thomas Wintour, and tell what had happened.

His belongings at Clopton—including several incriminating Catholic symbols—were also taken, and by the time the plotters had reached Catesby's family home at Ashby St Ledgers, Rookwood's name was among the list of suspects drawn up by the Lord Chief Justice.

Father Garnet, contacted at Coughton Court by Bates, wrote Catesby a letter in which he implored the group to stop their "wicked actions", before himself fleeing.

Through pouring rain they rode to Hewell Grange, helping themselves to further arms, ammunition and money, and finally reached Holbeche House, on the border of Staffordshire, at about 10:00 pm that night.

Then did he acknowledge his offence to be so heinous, that he justly deserved the indignation of the King, and of the Lords, and the hatred of the whole Common-wealth, yet could he not despair of Mercy at the hand of a Prince, so abounding in Grace and Mercy : And the rather, because his offence, though it were incapable of any excuse, yet not altogether incapable of some extenuation, in that he had been neither Author nor Actor, but onely perswaded and drawn in by Catesby, whom he loved above any worldly man : and that he had concealed it, not for any malice to the Person of the King, or of the State, or for any ambitious respect of his own, but onely drawn with the tender respect, and the faithful and dear affection he bore to Mr. Catesby his Friend, whom he esteemed more dear than any thing else in the world.

[33] Three days later, Digby, Robert Wintour, John Grant and Thomas Bates were hanged, drawn and quartered at the western end of St Paul's churchyard.

The following day, Rookwood, Thomas Wintour, Robert Keyes and Guy Fawkes were tied to wattled hurdles and dragged by horse from the Tower, to the Old Palace Yard at Westminster—a longer route than had been suffered by their fellow conspirators.