William Saurin (1757 – 11 February 1839) was an Irish barrister and politician. He was Attorney-General for Ireland from 1807 to 1822, and for much of that period he acted as the effective head of the Irish Government. He was unusual in an Irish Law Officer in that he never became a judge, nor apparently ever wished to be one. As an Ulster Protestant, and determined opponent of Catholic Emancipation, he incurred the enmity of Daniel O'Connell, who called him "the mortal foe", and worked for his removal from office.
Saurin was born in Belfast, second of the four sons of the Reverend James Saurin, Vicar of Belfast (died 1774) and his wife Jane Duff.James Saurin, Bishop of Dromore, was his younger brother.
The Saurins were of French Huguenot descent (Daniel O'Connell called William an "insolent transplanted Frenchman"). Originally from Nimes, they left France after the revocation of the Edict of Nantes in 1685. Even a century later, this episode, according to his friends, made a deep impression on William. Louis Saurin, the first of the family to settle in Ireland, (he was probably a brother of the celebrated preacher Jacques Saurin), was William's grandfather.
He was educated at Duboudien's School, a well-regarded private academy in Lisburn, and at the University of Dublin, where he took his Bachelor of Arts degree in 1777. He entered Lincoln's Inn and was called to the Bar in 1780. After a slow start in his profession he became one of its acknowledged leaders; despite his later eminence he was at first considered something of a "plodder".
Saurin was a passionate opponent of the Act of Union and endeavoured, without success, to persuade the Irish Bar as a body to oppose it. He then entered the Irish House of Commons as member for Blessington, largely to combat the Union.