Clifford George Evans was born on 17 February 1912 in Senghenydd, Glamorgan, the youngest of three children of an outfitter and a milliner. Welsh was his first language. When his father joined up during the First World War, young Clifford went to live with his maternal grandparents in Bronwydd, Carmarthenshire, and later attended Llanelli Intermediate School. In 1929 he moved to London and won a scholarship to the Royal Academy of Dramatic Art.
He made his professional stage debut in 1931 at the Embassy Theatre, Swiss Cottage, and his West End debut in 1933 when the Croydon production of Gallows Glorious transferred to the Shaftesbury Theatre. He went on to appear in many British films of the 1930s and, during the Second World War, registered as a conscientious objector and served in the Non-Combatant Corps while continuing to act, starring opposite Tommy Trinder in the Ealing wartime drama The Foreman Went to France (1942) and in The Flemish Farm (1943).
Evans continued to work steadily in British film and television through the 1950s and 1960s, including Violent Playground (1958) and SOS Pacific (1959), and took one of his best-remembered screen roles as Don Alfredo Corledo in the Hammer horror film The Curse of the Werewolf (1961), alongside Oliver Reed. Between 1965 and 1969 he became a household name playing the ruthless tycoon Caswell Bligh in the ITV drama The Power Game, and also appeared in Dr Finlay's Casebook, The Avengers, The Saint, The Prisoner and Jason King.
Away from acting, Evans was a committed advocate for Welsh theatre. He was appointed Director of Productions by Cardiff City Council for the 1951 Festival of Britain, and in 1957 founded the St David's Theatre Trust with the aim of establishing a National Theatre for Wales. He died on 9 June 1985 in Welshpool, Wales, at the age of 73.