Nonjuror, in British history, any of the beneficed clergy of the Church of England and the Episcopal Church in Scotland who refused to take the oaths of allegiance to William III and Mary II after the deposition of James II in the Glorious Revolution (1688–89). They numbered about 400 in England, including eight bishops and some of the most devout and learned men in the Anglican church. Among the most prominent of the Nonjurors were: the archbishop of Canterbury, William Sancroft; the saintly hymn writer Thomas Ken; the ecclesiastical polemicist Jeremy Collier; the historian Henry Dodwell; and Henry Hyde, 2nd earl of Clarendon. They considered William and Mary to be usurpers, adhered to their oaths to James II, but adopted a policy of nonresistance to the established authorities. From 1694 they maintained a separate ecclesiastical succession, but they were divided over liturgical usages, and their numbers dwindled in the 18th century; the last Nonjuror bishop died in 1805.
In Scotland the disestablishment of the Episcopal church in 1690 resulted in the defection of the greater part of the clergy. Unlike their Church of England counterparts, the Scottish Nonjurors actively supported the Stuart cause, participated in the Jacobite uprisings of 1715 and 1745, and suffered severe reprisals. In 1788, with the death of Charles Edward, the Young Pretender, the bishops agreed to recognize King George III.
A large number of Presbyterians in Scotland, principally among the Cameronians, also refused to take the oaths of allegiance to William and Mary, but as their refusal was on different grounds, they are not usually referred to as Nonjurors.