Anglican clergyman, author, poet, hymn-writer and pioneer ofWelsh Calvinistic Methodism, was born at Cefn-y-Coed, Llanfair-ar-y-bryn to the north of Llandovery, on 11 February 1717. During a brief period studying medicine at Llwyn-llwyd dissenting academy near Hay-on-Wye, he was converted under the preaching of Howell Harris. Ordained deacon in 1740, he served as a curate in Breconshire. In 1743, refused ordination as a priest, he joined the Methodists, became an assistant to the Rev. Daniel Rowland and began to concentrate on his literary work, aided by an inheritance. After his marriage, he settled at Pantycelyn farm, Pentre-ty-gwyn, east of Llandovery. He went on extensive preaching tours in both south and north Wales, and sided with Rowland when the rift with Howell Harris took place.
Sometimes called 'the sweet singer of Wales', he is particularly remembered for his hymns, mostly in Welsh. These numbered nearly a thousand and appeared in numerous collections between 1744 and 1790, including works in English. Three of his hymns in English translation appear in Hymns & Psalms, of which 'Guide me, O thou great Jehovah' (HP 437; SF 465) has become a firm favourite. He also composed, in Welsh, two epic poems of over 1,000 stanzas. His numerous prose works were intended for the edification of the converts, and he is today regarded as a formative figure and one of the giants of Welsh literature. He died at Pantycelyn on 11 January 1791 and is commemorated by an obelisk in the churchyard at Llanfair-ar-y-bryn and by a Memorial Chapel in Llandovery.
His son John Williams (1754-1828) was born at Pantycelyn and educated at Carmarthen Grammar School. He was ordained priest in 1780 and served briefly as a curate, but in 1781 opened a school at Coychurch and became a Methodist. In 1784 he became a tutor at Lady Huntingdon's college at Trevecka, where he was Principal from 1786 to 1791. He remained a leading figure in Welsh Methodism, taking part in the first ordination in 1811. He died at Pantycelyn and was buried with his father at Llanfair-ar-bryn.