Sir William Courtenay, 1st Baronet (7 September 1628 – 1 August 1702) was an English politician.
Courtenay was the eldest son and heir of Francis Courtenay (d.1638) of Powderham Castle by his second wife Elizabeth Seymour, daughter of Sir Edward Seymour, 2nd Baronet.
He was created a baronet in 1644 by King Charles I but disdained the newly invented variety of title, perhaps on political grounds, and never took out a patent. He was therefore not included in the list of baronets, although the king styled his as such in his commissions.
On 2 April 1660, Courtenay became the Member of Parliament (MP) for Ashburton, Devon. However, he retired from politics after the Restoration and appears not to have been returned in 1661. In 1664 he served as High Sheriff of Devon. In 1677 Courtenay's health prevented him standing for Ashburton but he managed the campaign of the country party. The country party's candidate was unsuccessful, but the government supporters admitted that in a clean election Courtenay's campaign had been very moderate. Notwithstanding that, he had made a new freeholder and "drank him so freely" that he fell downstairs and broke his neck. On 18 February 1679, Courtenay became MP for Devon until 1685. His health prevented him standing in 1688.
After the Glorious Revolution of 1688, Courtenay funded a lavish reception at Forde House, Wolborough, for William of Orange and his council, who had just landed nearby at Torbay. He was not himself present as host, having felt it prudent not to associate himself too strongly to the new regime should it fail. The chair on which the future King William III sat during his first Council of State at Forde is now displayed in the Dining Hall of Powderham Castle.