There are at least two artists called John Thomas.
1) 19th-century Welsh harpist and composer;
2) American keyboardist, associated with Captain Beefheart and Bruce Hornsby. 1) John Thomas ('Pencerdd Gwalia') (1826-1913), harpist and composer, was born in Bridgend, Glamorgan. In 1838, he won the triple harp at the Abergavenny eisteddfod. In 1840, he went to the Royal Academy of Music, and was made a Fellow on his departure in 1846.