Sir William Glynne, 1st Baronet (20 January 1638 – 8 September 1690) was a Welsh politician.
William was the son of Sir John Glynne, the Lord Chief Justice during the Commonwealth.
He was educated at Jesus College, Oxford, taking his degree in 1656, and represented Caernarfon in the Third Protectorate Parliament.
William was again returned for Caernarfon during the Convention Parliament, and was subsequently created a baronet, of Bisseter, Oxfordshire, on 20 May 1661.
By his wife Penelope Anderson, Glynne had two surviving sons and two daughters.