Gwillim also featured in over sixty films and television series, usually war films or historical epics. His military background, commanding presence and deep, booming voice typecast him as Soldiers and authority figures. Some of his most notable roles include playing a warship captain in Sink the Bismarck! (1960), the archbishop Hubert Walter in Sword of Sherwood Forest (1960), the obnoxious club secretary in Lawrence of Arabia (1962), King Aeëtes in Jason and the Argonauts (1963), an RAF officer in the James Bond film Thunderball (1965), the Lord Chief Justice in A Man for All Seasons (1966), General Harold Alexander in Patton (1970), Poseidon in Clash of the Titans (1981), and Van Helsing in The Monster Squad (1987). He also had a recurring role on the TV series Danger Man, The Saint, and The Troubleshooters.