Williams was educated in Geneva and at Christ Church, Oxford. In the 1930s and '40s he wrote some immensely successful plays, which contained starring parts for himself. The best-known of these was Night Must Fall (performed 1935) in which he played the baby-faced killer, Danny, and which was later made into two film adaptations. Williams' other plays include A Murder Has Been Arranged (1930), The Corn Is Green (1938), also made into a film (1945), and The Druid's Rest (1944). He acted in many films and was also renowned for his public readings from the works of Charles Dickens, Dylan Thomas, and Saki. He wrote two volumes of autobiography, George (1961) and Emlyn (1973). Beyond Belief (1967) and Headlong (1980) are adventure novels.