Rhys Haydn Williams (14 July 1930 – 27 January 1993), born in Cwmllynfell, was a Welsh rugby union player who gained 23 caps for Wales as a lock.
Rhys Williams (height 6 ft 3 in, weight 16 st 10 lb) was educated at Ystalyfera Grammar School and Cardiff University. He made his debut in club rugby for Llanelli at the age of nineteen, going on to captain the club in the 1957–58 season. After graduating he joined the RAF as an Education Officer, playing in the Inter-Services tournament and for Combined Services, later becoming a research chemist and Assistant Director of Education for Mid Glamorgan.
He made his debut for Wales in 1954 against Ireland and played at international level until 1960, captaining Wales against England in that year. He played for the British and Irish Lions, going on the 1955 Lions tour to South Africa and the 1959 tour to Australia and New Zealand. On these tours he played in ten consecutive test matches. He also toured Canada and South Africa with the Barbarians. In the final test against New Zealand in 1959, he won the last six line-outs to deny New Zealand the chance to equalize.He was the only forward to be named as 'Player of the Year' in New Zealand during the 1959–1960 season.
Andrew Bennett in his book Welsh Rugby Heroes includes R.H. Williams at No. 4 in his selection of the "all-time greatest" Welsh XV.