Ieuan Gwyllt was the bardic name of Welsh musician and minister John Roberts (22 December 1822 - 14 May 1877). His bardic name is derived from the nome de plume he used whilst writing poetry as a boy, 'Ieuan Gwyllt Gelltydd Melindwr' (John of the Wild Woods near the Mill Tower). He was born at Tanrhiwfelen, a house just outside Aberystwyth, and died in Caernarfon on 14 May 1877. He was buried at Caeathro cemetery near Caernarfon.
Roberts worked as a clerk to a company of druggists in Aberystwyth, but after two years started to teach at the Skinner Street School. After only a few months, however, he enrolled at the Borough Road Training College in London where he stayed for nine months. On his return to Aberystwyth in 1845 he opened a school. After only nine months there, however, he left to become clerk to a firm of solicitors where he stayed for nearly seven years. In 1852 he became assistant editor of Yr Amserau, a Welsh newspaper based in Liverpool.
On 15 June 1856 he preached his first sermon at Runcorn and in 1858 he moved to Aberdare to edit Y Gwladgarwr ("The Patriot"). The following year he was married to Jane Richards of Aberystwyth. In 1859 he was asked to become minister of Pant-tywyll Calvinistic Methodist church in Merthyr Tydfil and was ordained on 7 August 1861 at the Newcastle Emlyn Association.
Although composing music from an early age, it was not until 1859 that he produced Llyfr Tonau Cynulleidfaol a labour of some six years, with which publication began a new era of Welsh congregational hymn singing. Roberts founded a number of regional musical festivals - the Gwent and Morgannwg in 1854, the Gŵyl Eryri in 1866, and the Gŵyl Ardudwy in 1868. In the 1870s he travelled widely throughout Wales, lecturing on congregational music.