William Salesbury (c. 1520 - c.1584) was the principal author of the first Welsh translation of the New Testament, published in 1567.
Salesbury was born in about 1520 in the parish of Llansannan in Wales. He was educated at Oxford University, where he studied the Hebrew, Greek and Latin languages, and also became familiar with the (banned) writings of Martin Luther and William Tyndale as well as the technology of printing. In 1547, he produced an English-Welsh dictionary. However, as a Protestant, he was obliged to spend most of the reign of Mary I of England in hiding.
Salesbury was both a scholar and a deeply religious man as well as an ardent supporter of Wales and the Welsh language. He was the author of a number of books in Welsh, including Oll Synnwyr pen Kembero ygyd (All the Welshman's Wisdom) and Kynniver llith a ban (All the lessons and articles).
The belief of Erasmus and Luther that the Bible should be available to all in their native language was firmly advocated by Salesbury. In 1563, he helped instigate the act of parliament under which this became a priority. With the consent of the leading Welsh bishops of the time, he prepared a translation of the New Testament from the original Greek into Welsh. This was published on 7 October 1567. Salesbury also translated the English Book of Common Prayer into Welsh, which was also published (as Llyfr Gweddi Gyffredin) in 1567.