Sir John Prise (also Prys, Price, in Welsh Syr Siôn ap Rhys) (ca. 1502–1555) was a Welsh public notary, who acted as a royal agent and visitor of the monasteries. He was also a scholar, associated with the first Welsh printed publication Yn y lhyvyr hwnn. He was a Member (MP) of the Parliament of England for Breconshire in 1547; Hereford October 1553; Ludlow April 1553; and Ludgershall November 1554.
He was son of Rhys ab Gwilym by Gwenllian, daughter of Howel Madoc. He was educated at All Souls College, Oxford, and the Middle Temple, and became a notary public and receiver of the king. From a statement of Rowland Lee, it appears that Prise had been some time in the service of the Earl of Arundel as constable of Cloon Castle in Ireland, and that for his employment he was promoted to be one of Thomas Cromwell's agents.
In May 1532, when the Earls of Westmorland and Cumberland and Sir Thomas Clifford searched Cuthbert Tunstall's house at Bishop Auckland, Price looked into the manuscripts, and made a report to Cromwell. In 1533 he was employed under Cromwell. In 1534 he was registrar of Salisbury Cathedral. In April 1535 he took part in the proceedings against the Carthusians as to the royal supremacy. He officiated in the same way at the trial of John Fisher and Thomas More. He took part in the major visitation of the monasteries of 1535, alongside Sir Thomas Legh. When the Pilgrimage of Grace was quelled, he assisted in trying the rebels. For his services he received in 1537-8 a joint lease of Carmarthen rectory, and a lease of Brecon Priory and rectory. He also bought the priory of St. Guthlac, Hereford. In a petition of 1538 he asked for the manor of West Dereham.