William Jenkyn Thomas (5 July 1870 – 14 March 1959) was a Welsh author best known for his The Welsh Fairy Book. He was an undergraduate student at the University of Cambridge and in addition to his writings worked as a lecturer and teacher. He was the first Head Master at Aberdare Intermediate School (1896-905) and was headmaster (1905-1935) at Hackney Downs School.
Thomas, W. J. (1894). Penillion telyn, Rhan 1. Caernarfon: Gwymni y Cyhoeddwys Cymreig.
Thomas, W. J. (1870). Cambrensia: A literary reading book for Welsh schools. London: Edward Arnold.
Thomas, W. J. (1907). The Welsh fairy book. London: Fisher Unwin.