Major Ronald Owen Lloyd Armstrong-Jones MBE QC (18 May 1899 – 27 January 1966) was a British barrister and soldier and the father of Antony Armstrong-Jones, 1st Earl of Snowdon.
The only son of Sir Robert Armstrong-Jones, a psychiatrist, he was educated at Eton, then during the First World War was commissioned as a Second Lieutenant into the Royal Regiment of Artillery. After the war he continued his education at Magdalen College, Oxford, graduating in 1922, then became a barrister in the Inner Temple. During the Second World War he returned to the army and served as a Major in the King's Royal Rifle Corps; he was invalided out in 1945, after serving as Deputy Judge Advocate to Montgomery's staff in Normandy. A liveryman of the Worshipful Company of Clothworkers, from 1955 to 1959 he was a member of the Industrial Disputes Tribunal. He also served as a Governor of St Bartholomew's Hospital.
In 1936 Armstrong-Jones served as High Sheriff of Caernarvonshire.
Armstrong-Jones was married three times. Firstly, on 22 July 1925, to Anne Messel (8 February 1902 – July 1992); after having two children, Antony (1930–2017), the brother-in-law of Queen Elizabeth II, and Susan (1927–1986), who married John Vesey, 6th Viscount de Vesci, they divorced in 1934, and Anne later married the 6th Earl of Rosse. On 18 June 1936 Armstrong-Jones married secondly Carol Akhurst; they divorced in 1959, and Carol was killed in a car crash in 1966. He married thirdly Jenifer Unite on 11 February 1960 and they had one son, Peregrine Armstrong-Jones (born 1960). Jenifer Unite, an air hostess, was the daughter of Basil Unite, a major fruit importer. Antony Armstrong-Jones attended his father's last wedding.