William Williams Pantycelyn (c. 11 February 1717 – 11 January 1791), also known as William Williams, William Pantycelyn, and Pantycelyn, is generally seen as Wales's most famous hymn writer. As a writer of both poetry and prose, he is today considered one of the great literary figures of Wales. He was equally distinguished in the world of religion, as one of the key leaders, along with Howell Harris and Daniel Rowland, of the 18th-century Welsh Methodist revival.
Williams was born at Cefn-coed farm in the parish of Llanfair-ar-y-bryn, near the town of Llandovery (Llanymddyfri), in 1717, the son of John and Dorothy Williams. John died in 1742, and Dorothy later moved to the nearby farm of Pantycelyn ("Holly Hollow"). The family were Nonconformists. William Williams was educated locally and then at a nonconformist academy near Talgarth.
He had intended to become a doctor, but this changed in 1737/38, when he was converted by the preaching of the evangelical Methodist revivalist Howell Harris in Talgarth.
For much of his life, Williams lived in the parish of Llanfair-ar-y-bryn, near the town of Llandovery (Llanymddyfri). He died at Pantycelyn in January 1791, at the age of 74, and is buried in Llanfair-ar-y-bryn churchyard. He is also commemorated by a memorial chapel in Llandovery.
William Williams felt called to the priesthood; and in 1740, despite his family's links with the Nonconformist branch of Christianity, he took deacon's orders in the Established Anglican Church. (Since disestablishment in 1920, the Anglican church in Wales has been known as the Church in Wales.)