Gilbert Burnet (18 September 1643 – 17 March 1715) was a Scottish philosopher and historian, and Bishop of Salisbury. He was fluent in Dutch, French, Latin, Greek, and Hebrew. Burnet was highly respected as a cleric, a preacher, an academic, a writer and a historian. He was always closely associated with the Whig party, and was one of the few close friends in whom King William III confided.

Burnet was born at Edinburgh, Scotland, in 1643, the son of Robert Burnet, Lord Crimond, a Royalist and Episcopalian lawyer, who became a judge of the Court of Session, and of his second wife Rachel Johnston, daughter of James Johnston, and sister of Archibald Johnston of Warristoun, a leader of the Covenanters. His father was his first tutor until he began his studies at the University of Aberdeen, where he earned a Master of Arts in Philosophy at the age of thirteen. He studied law briefly before changing to theology. He did not enter into the ministry at that time, but travelled for several years. He visited Oxford, Cambridge, London, the United Provinces and France. He studied Hebrew under a Rabbi in Amsterdam. By 1665 he returned to Scotland and was ordained in the Church of Scotland (then episcopal) by the bishop of Edinburgh. In 1664 he was elected a Fellow of the Royal Society.

He began his ministry in the rural church at East Saltoun, East Lothian, and served this community devoutly for four years. In 1669, without his being asked, he was named to the vacant chair of Divinity at the University of Glasgow. At first he declined, since his congregation unanimously asked him to remain at East Saltoun; but, when the Bishop of Edinburgh, Leighton, urged him, he accepted the post. He was later offered, but declined, a Scottish bishopric.

In 1672 or 1673 he privately married Lady Margaret Kennedy, daughter of the Earl of Cassilis, who was many years his senior. The great differences between the couple in age, rank and fortune caused them to keep the marriage secret for a considerable time. Burnet's motives for marriage were certainly not mercenary, as he entered into what has been described as an early form of "pre-nuptial agreement" by which he renounced any claim to his wife's money. Burnet himself recalled that they had been good friends for several years, but that in his view such a close friendship between a single man and a single woman could not continue indefinitely unless they married. The marriage seems to have been happy, despite their lack of children, which Burnet regretted. He was to have numerous children by later marriages.

In view of the unsettled political times, he left the university in 1674 and moved to London. In London, his political and religious sentiments prompted him to support the Whigs. His energetic and bustling character led him to take an active part in the controversies of the time, and he endeavoured to bring about a reconciliation between Episcopacy and Presbytery.

At Court, where his brother Thomas was a royal physician, he gained the favour of Charles II, from whom he received various preferments. He described Charles shrewdly as a man who, despite his affable manner and famed courtesy, was at heart the archetypal cynic: "he has a very ill opinion of men and women, and so is infinitely distrustful... he thinks the world is governed wholly by (self) interest". Burnet noted fairly that this attitude was quite understandable, given the King's experiences in the English Civil War and the Interregnum, which had shown him when he was still very young the "baseness of human nature". Like many other observers he noted Charles's remarkable self-control: "he has a strange command of himself: he can pass from business to pleasure, and from pleasure to business, in so easy a manner that all things seem alike to him." He also recorded some of the King's most memorable sayings, such as "Appetites are free, and Almighty God will never damn a man for allowing himself a little pleasure".

During the Popish Plot, when Queen Catherine was accused of treason, (it was alleged that she had conspired to murder her husband), the King confided to Burnet his feelings of guilt about his ill-treatment of the Queen, "who is incapable of doing a wicked thing", his resolve not to abandon her ("it would be a horrible thing, considering my faultiness to her"), and his wish to live a more moral life in future. Burnet, for his part, told the King frankly that he was wrong to believe that the Earl of Shaftesbury had any part in the charges of treason made against the Queen: Shaftesbury, who was well aware of the Queen's great popularity with the English ruling class, was simply too shrewd a statesman to make such a serious political misjudgment.

As regards the reality of the Plot itself, while the King quickly became a total sceptic on the subject, Burnet probably captures Charles's first reaction to the accusations neatly enough: "among so many particulars I do not know but there may be some truth." Burnet himself was neither a sceptic, nor a convinced believer in the Plot. Like most sensible Protestants he believed that there had probably been a Catholic conspiracy of some sort, but he had grave doubts about the veracity of the informers, especially Titus Oates, while he regarded Israel Tonge, the co-author of the Plot, as insane. He recognised the danger that innocent people might be falsely accused, and it is notable that he praised the Catholic martyr Oliver Plunkett, Archbishop of Armagh, who is nowadays probably the best-known victim of the Plot, as a good and innocent man who was destroyed by the malice of his personal enemies. He also argued strongly that the first victim of the Plot, the young Catholic banker William Staley, was innocent, although his narrative of Staley's trial was undoubtedly coloured by his detestation of William Carstares, the Crown's chief witness at Staley's trial. Whether the Catholic nobleman William Howard, 1st Viscount Stafford, executed for treason in 1680, was innocent or guilty he regarded as a mystery whose solution must await "the great revelation of all secrets".