William Mowse (Mouse, Mosse) (died 12 August 1588) was an English lawyer and Master of Trinity Hall, Cambridge.
In the latter year, through the interest of Thomas Cranmer and William Cecil, he obtained the mastership of Trinity Hall on the removal of Walter Haddon.
In July 1555, he subscribed the Marian articles of religion, and on Gardiner's death, 12 November, the mastership of Trinity Hall was restored to him.
Though deprived of the Oxford chair and of the mastership of Trinity Hall soon after the accession of Elizabeth I, Mowse was in 1559 constituted vicar-general and official of the Archbishop of Canterbury, dean of the arches, and judge of the court of audience.
In 1564, he sat on a commission, appointed 27 April, to try admiralty causes arising from depredations alleged to have been committed by English privateers on Spanish commerce.