The Popish Plot was a fictitious conspiracy concocted by Titus Oates that gripped England, Wales and Scotland in Anti-Catholic hysteria between 1678 and 1681. Oates alleged that there existed an extensive Catholic conspiracy to assassinate Charles II, accusations that led to the execution of at least 15 men and precipitated the Exclusion Bill Crisis. Eventually Oates' intricate web of accusations fell apart, leading to his arrest and conviction for perjury.

The fictitious Popish Plot was exacerbated by many historical events in the sixteenth century and was only believed because circumstances before 1678 had increased anti-Catholic sentiment among the mostly Protestant population of England. Anti-Catholic fears are observed as early as 1533 with the English Reformation. Also, the Ridolfi plot in 1571, the Babington Plot of 1580, and the Gunpowder Plot of 1605 all contributed to anti-Catholic feeling. The rule of Mary I, the attack of the Spanish Armada, and the Great Fire of London in 1666 were other events that were important contributors to anti-Catholic sentiment and intensified Protestant hatred of Catholics, making the plot against Charles II seem believable.

Charles II (29 May 1630 – 6 February 1685) was king of England, Scotland, and Ireland.

Charles II's father, King Charles I, was executed at Whitehall on 30 January 1649, at the climax of the English Civil War. Although the Parliament of Scotland proclaimed Charles II King of Great Britain and Ireland in Edinburgh on 6 February 1649, the English Parliament instead passed a statute that made any such proclamation unlawful. England entered the period known as the English Interregnum or the English Commonwealth, and the country was a de facto republic, led by Oliver Cromwell. Cromwell defeated Charles at the Battle of Worcester on 3 September 1651, and Charles fled to mainland Europe. Cromwell became virtual dictator of England, Scotland and Ireland. Charles spent the next nine years in exile in France, the United Provinces and the Spanish Netherlands.

A political crisis that followed the death of Cromwell in 1658 resulted in the restoration of the monarchy, and Charles was invited to return to Britain. On 29 May 1660, his 30th birthday, he was received in London to public acclaim. After 1660, all legal documents were dated as if Charles had succeeded his father as king in 1649.

Sir Henry Pollexfen (1632 – June 15, 1691) was a British judge and politician. He was the son of Andrew Pollexfen and his wife Joan, and the brother of John Pollexfen, the British political economist. He entered Inner Temple in 1652, was called to the bar in 1658 and by 1662 he was pleading before the high courts at Westminster Hall. In 1674 he became a bencher at Inner Temple, and was the leading practitioner on the western circuit, frequently pleading at the King's Bench. In 1676 he defended Stockbridge, Hampshire on a Quo warranto charge, which he lost. He frequently acted as counsel in various politically charged cases, and regularly lost; clients included the lords involved in the Popish Plot, the Earl of Danby and as one of many counsel for Edward Fitzharris, Stephen College and Algernon Sidney, all of whom were later executed. Along with Sir George Treby and Sir Francis Winnington he defended London on a second Quo warranto charge in 1683, arguing that Corporations could not be charged for the wrongdoing of individuals. He lost, and in 1684 was asked to take a similar case for Berwick-upon-Tweed, this time advising surrender.

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.

Chidiock (Charles) Tichborne (1563 – 20 September 1586) is remembered as an English conspirator and poet.

He was born in Southampton sometime after 24 August 1562 to Roman Catholic parents, Peter Tichborne and his wife Elizabeth (née Middleton). His birth date has been given as circa 1558 in many sources, though unverified, and thus his age given as 28 at his execution. It is unlikely that he was born before his parents marriage so he could have been no more than 23 years old when he died.

Chidiock's father Peter appears to be the youngest son of Henry Tichborne (born circa 1474) and Anne Mervin (or Marvin) but the records are unclear. Peter was clerk of the Crowne at the trial of Sir Nicholas Throckmorton in 1554 and was an ardent catholic supporter. Being the youngest son of a youngest son he was of little means and required to make his own way. He secured an education and the patronage of Lord Chidiock Paulet. In later life he spent many years imprisoned unable to pay recusancy fines. Chideock's mother was Elizabeth Middleton, daughter of William Middleton (grandson of Sir Thomas Middleton of Belso, Kt.) and Elizabeth Potter (daughter of John Potter of Westram). William had been servant to John Islip, Abbot of Westminster, and a banner bearer at Islip's funeral 1532 , and later bought lands in Kent.