William Salesbury also Salusbury (c. 1520 – c. 1584) was the leading Welsh scholar of the Renaissance and the principal translator of the 1567 Welsh New Testament.
Salesbury was born some time before 1520 in the parish of Llansannan, Conwy. He was the second son of Ffwg Salesbury (d. 1520) and Annes, daughter of Wiliam ap Gruffydd ap Robin o Gochwillan. By 1540 he had moved to Plas Isa, Llanrwst; this had been the residence of both his father and his brother. He was probably educated locally, and was certainly influenced by the literary traditions of the Vale of Clwyd. He then studied at Oxford University, probably living in Broadgates Hall. Here he studied the Hebrew, Greek and Latin languages, and became familiar with the (banned) writings of Martin Luther and William Tyndale as well as the technology of printing. Here too he was caught up in the renaissance of learning. Mathias suggests that it was at Oxford that Salesbury left the Roman Catholic church and became a Protestant. Although there is no record of his either having taken a degree at Oxford or having gone on to one of the inns of court, it is known that in 1550 he was at Thavies Inn. Although he spent considerable time in London, there is no evidence of his having travelled abroad. His wife was Catrin Llwyd, sister of Ellis Price. She died around 1572.
Brinley Jones describes the remarkable range of Salesbury's writings, "the product of a Renaissance humanist scholar, lexicographer, and translator". Mathias describes his motivations as making the Bible available to the Welsh people, and imparting knowledge to them in their own language. In 1547, Salesbury produced an English-Welsh dictionary called A dictionary in Englyshe and Welshe, printed by John Waley ‘at London in Foster Lane’ in 1547. Mathias conjectures that this may have been the first book to be printed in Welsh. Brinley Jones suggests that the dictionary has the appearance of a work-book, devised in the first place for Salesbury's own use. In 1550 his A briefe and a playne introduction, teachyng how to pronounce the letters in the British tong (now commonly called Walsh)... was printed by Robert Crowley. A revised edition was printed "by Henry Denham for Humphrey Toy, at the sygne of the Helmet in Paules church yarde, The. xvij. of May. 1567." A short comparative study of Welsh sounds with Hebrew and Greek is included, plus an examination of the Latin element in Welsh (which he had first examined in the dictionary of 1547). Both of these books have become important sources for information about the spoken English of the sixteenth century.