Captain Iolo Aneurin Williams (18 June 1890 – 18 January 1962), was a British writer, journalist and Liberal Party politician. His son was the composer Edward Williams.

Williams was born in Middlesbrough, the son of Aneurin Williams, who was a Liberal member of parliament. He was the brother of Ursula Williams who was also a Liberal politician. He was educated at Rugby School and King's College, Cambridge. In 1920 he married Francion Elinor Dixon. They had one son and two daughters.^[1]

Williams was Bibliographical Correspondent of the London Mercury from 1920–1939. He made contributions to the Dictionary of National Biography and the Cambridge Bibliography of English Literature. He was a published poet and writer.^[2]

• Poems, 1915
• New Poems, 1919
• Byways Round Helicon, 1922
• Shorter Poems of the 18th Century, 1923
• Seven 18th Century Bibliographies, 1924
• Editor: plays of Sheridan, 1926
• Elements of Book-Collecting, 1927
• Poetry To-day, 1927
• Where the Bee Sucks, 1929 (illustrated by Katharine Cameron)
• The Firm of Cadbury, 1931
• Points in 18th Century Verse, 1934
• English Folk Song and Dance, 1935
• Flowers of Marsh and Stream (King Penguin), 1946
• Early English Water-Colours, 1952

Williams was Liberal candidate for the Chelsea division of London at the 1924 General Election. Chelsea was a safe Unionist seat, so he was not expected to win. 1924 was not a good election for the Liberals and he came in third place in the race. Despite this, he contested Chelsea again at the 1929 General Election, a better election for the Liberals. He increased the Liberal share of the vote, but still finished third. He did not stand for parliament again.^[3]

• Katharine Cameron
• Arthur St John Adcock