Robert Catesby (b. in or after 1572 – 8 November 1605), was the leader of a group of provincial English Catholics who planned the failed Gunpowder Plot of 1605.
Most probably born in Warwickshire, Catesby was educated in nearby Oxford. His family were prominent recusant Catholics, therefore presumably to avoid swearing the Oath of Supremacy he left college before taking his degree. He married a Protestant in 1593 and fathered two children, one of whom survived and was baptised in a Protestant church, but in 1598, following the deaths of his father and wife, he may have reverted to Catholicism. In 1601 he took part in the Essex Rebellion but was captured and fined, after which he sold his estate at Chastleton.
The Protestant James I, who became King of England in 1603, was less tolerant of Catholicism than its followers had hoped. Catesby therefore planned to kill him by blowing up the House of Lords with gunpowder, the prelude to a popular revolt during which a Catholic monarch would be restored to the English throne. Early in 1604 he began to recruit other Catholics to his cause, including Thomas Wintour, John Wright, Thomas Percy, and Guy Fawkes. Described latterly as a charismatic and influential man, as well as a religious zealot, over the following months he helped bring a further eight conspirators into the plot, whose naissance was planned for 5 November 1605. A letter sent anonymously to William Parker, 4th Baron Monteagle, alerted the authorities, and on the eve of the planned explosion, during a search of Parliament, Fawkes was found guarding the barrels of gunpowder. News of his arrest caused the other plotters to flee London, warning Catesby along their way.
With a much-diminished group of followers, Catesby made a stand at Holbeche House in Staffordshire, against a 200-strong company of armed men. He was shot, and later found dead, clutching a picture of the Virgin Mary. As a warning to others, his body was exhumed and his head exhibited outside Parliament.