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.

Guy Fawkes (13 April 1570 – 31 January 1606), also known as Guido Fawkes, the name he adopted while fighting for the Spanish in the Low Countries, belonged to a group of provincial English Catholics who planned the failed Gunpowder Plot of 1605.

Fawkes was born and educated in York. His father died when Fawkes was eight years old, after which his mother married a recusant Catholic. Fawkes later converted to Catholicism and left for the continent, where he fought in the Eighty Years' War on the side of Catholic Spain against Protestant Dutch reformers. He travelled to Spain to seek support for a Catholic rebellion in England but was unsuccessful. He later met Thomas Wintour, with whom he returned to England.

Wintour introduced Fawkes to Robert Catesby, who planned to assassinate King James I and restore a Catholic monarch to the throne. The plotters secured the lease to an undercroft beneath the House of Lords, and Fawkes was placed in charge of the gunpowder they stockpiled there. Prompted by the receipt of an anonymous letter, the authorities searched Westminster Palace during the early hours of 5 November, and found Fawkes guarding the explosives. Over the next few days, he was questioned and tortured, and eventually he broke. Immediately before his execution on 31 January, Fawkes jumped from the scaffold where he was to be hanged and broke his neck, thus avoiding the agony of the mutilation that followed.

Aleister Crowley (/ˈkroʊli/ KROH-lee; 12 October 1875–1 December 1947), born Edward Alexander Crowley, and also known as both Frater Perdurabo and The Great Beast, was an influential English occultist, mystic, ceremonial magician, poet and mountaineer, who was responsible for founding the religious philosophy of Thelema. In his role as the founder of the Thelemite philosophy, he came to see himself as the prophet who was entrusted with informing humanity that it was entering the new Aeon of Horus in the early 20th century.

Born into a wealthy upper class family, as a young man he became an influential member of the esoteric Hermetic Order of the Golden Dawn after befriending the order's leader, Samuel Liddell MacGregor Mathers. Subsequently believing that he was being contacted by his Holy Guardian Angel, an entity known as Aiwass, while staying in Egypt in 1904, he "received" a text known as The Book of the Law from what he believed was a divine source, and around which he would come to develop his new philosophy of Thelema. He would go on to found his own occult society, the A∴A∴ and eventually rose to become a leader of Ordo Templi Orientis (O.T.O.), before founding a religious commune in Cefalù known as the Abbey of Thelema, which he led from 1920 through till 1923. After abandoning the Abbey amid widespread opposition, Crowley returned to Britain, where he continued to promote Thelema until his death.