The New Cambridge Shakespeare introduction praised these Lears: (top to bottom) Christopher Plummer, Donald Wolfit (in the 1940s) and Robert Stephens. Wolfit was the model for the actor in the Ronald Harwood play, The Dresser. The film version starring Albert Finney showed parts of a couple of touring productions of King Lear. (Like the Slings and Arrows story, the actor dies shortly after dying as Lear. Wolfit didn't, though.) Robert Stephens RSC performance was called the greatest of his life. Oddly, he was in David Warner's first film, Morgan! It was also Vanessa Redgrave's first film. As far as I know she's never played Lear, though her brother Colin and her father Michael did. But with Stephens and Warner, this 60s comedy had two future Lears.