William Carstares (also Carstaires; 11 February 1649 – 28 December 1715) was a Scottish minister who was Moderator of the General Assembly of the Church of Scotland in 1705, 1708, 1711 and 1715.

Through Fagel he met the Prince of Orange, the future King William III of England and II of Scotland, and began to take an active part in politics.

He was believed to be concerned with Sir James Stewart in the authorship of a pamphlet An Account of Scotland's Grievances by reason of the D. of Lauderdale's Ministrie, humbly tendered to his Sacred Majesty (1674).

After this, Carstares visited Ireland, joined nonconformist circles in London, and then in 1681 became pastor to a congregation at Theobalds, near Cheshunt in Hertfordshire.

Carstares provided liaison, while his brother-in-law William Dunlop was able to use his colonial project in the Province of Carolina as cover for Shaftesbury's preparations for rebellion.

[2] In July 1684 the Privy Council of Scotland tortured William Spence, Argyll's agent, and Carstares was implicated.

The next day John Drummond, Secretary of State in Scotland, made a deal with Carstares that his answers would not be used in court, and had a doctor see him.

Carstares was freed, and went to London, and then to The Hague shortly before the Monmouth Rebellion, as an adviser to the Prince of Orange.

[1] He advocated that a Presbyterian polity should replace the Scottish bishops, and the immediate events of the Williamite conflicts bore out his opinion in practical terms.

During Anne's reign, the chief object of his policy was to frustrate the measures which were planned by Lord Oxford to strengthen the Episcopalian Jacobites, especially a bill for extending the privileges of the Episcopalians and the bill for replacing in the hands of the old patrons the right of patronage, which by the Revolution Settlement had been vested in the elders and the Protestant heritors.

The grave lies amongst the large monuments on the outer walls of the original churchyard, towards the southwest, slightly northwest of the Adam mausoleum.