Sir John Gielgud (1904–2000) was a British actor and director who, as well as his success in more modern roles, was known for his mastery of Shakespearean verse and is widely regarded as the best Hamlet of his generation. Gielgud played Lear on the stage four times during his long career: in 1930–1931, 1940, 1950 and 1955. He also recorded a radio production in 1994 at the age of 90.

In the 1940 production of King Lear at the Old Vic, Gielgud benefited from the instruction of the ground-breaking Shakespearean actor and director Harley Granville-Barker (1877–1946), who came out of retirement to take rehearsals for ten days. Barker and Gielgud focused on emphasizing Lear’s strength and power in his performance, despite Gielgud’s relative youth (he was 36) and slight frame. This was echoed in the costume and apparatus: Gielgud’s hair and beard were also moulded to make his face look chunky, he wore a voluminous cloak to add to his stature and in the final scene he used a hidden sling so he could carry Cordelia in one arm to show great physical strength. Barker and Gielgud also worked on creating a volatile and varied Lear, who quickly shifted from one mood or manner to another.