Andrew Willet (1562 – 4 December 1621) was an English clergyman and controversialist. A prolific writer, he is known for his anti-papal works. His views were Calvinist, conforming and non-separatist, and he appeared as a witness against Edward Dering before the Star-chamber. Joseph Hall (who knew him well) eulogised Willet in Noah's Dove, and Thomas Fuller modelled 'the Controversial Divine' of his Holy State on him.
He was born at Ely in 1562, son of Thomas Willet (1511?–1598), who began his career as a public notary, and later in life he took holy orders, becoming rector of Barley, Hertfordshire, fourteen miles from Cambridge and admitted to a prebendal of Ely by his patron, Bishop Richard Coxe, with whom he had been associated as sub-almoner to Edward VI.
Andrew had one brother and four sisters. After attending the collegiate school at Ely, he entered Cambridge University, matriculating at the age of fifteen (20 June 1577); he first went to Peterhouse, the master of which was Andrew Perne, his godfather, but in the same year moved to Christ's College, Cambridge. He was quickly elected a scholar, graduated B.A. in 1581, was elected to a fellowship at Christmas 1583 (aged twenty-one), proceeded M.A. in 1584, and in the same year was incorporated a member of the university of Oxford. He was B.D. in 1591, and D.D. 1601. Among the fellows of Christ's, he was on good terms with George Downham, and when Willet spent his vacations at his father's rectory of Barley, he was often accompanied by Downham. He took holy orders in 1585, and was admitted on 22 July 1587, on the presentation of the queen, to the prebendal stall at Ely, which his father had resigned in his favour.