William Llewelyn Williams known as Llewelyn Williams (10 March 1867 – 22 April 1922), was a Welsh journalist, lawyer and radical Liberal Party politician.
He was born at Brownhill, Llansadwrn, Towy Valley, Carmarthenshire, the second son of Morgan Williams and his wife Sarah (née Davies). A memorial plaque was erected in front of the house in 1938. Born into a prosperous Congregationalist family, his grandfather Morgan Williams had been an elder at Capel Issac near Llandeilo, before moving from Ffrwd-wen to his new residence at Brownhill. His uncle, John Williams (1819–69) was an Independent minister at Llangadog and later at Newcastle Emlyn and Capel Iwan. Another uncle, Benjamin Williams (1830–86) was also an Independent minister, serving at Gwernllwyn, Dowlais; Denbigh; and Canaan, Swansea.
Williams was educated at Llandovery College and Brasenose College, Oxford University. At Oxford he was among the earliest members of the Dafydd ap Gwilym Society, a grouping for Welsh-speaking undergraduates, together with O. M. Edwards, John Morris-Jones, Edward Anwyl, John Puleston Jones and Daniel Lleufer Thomas. Members of the Society saw themselves as agents of a cultural awakening, although it remained strictly non-political.
While a student at Oxford, he participated in the vigorous debates which took place in his home constituency of East Carmarthenshire to choose a Liberal candidate for the 1890 by-election following the death of David Pugh.