Harley Granville Barker was one of the more important British playwrights of the early 20th century. The actor-manager famously penned The Voysey Inheritance, which premiered at the Royal Court Theatre in 1905. However, as I was recently reminded by an issue of The Shavian, he also appeared as an actor in a number of the plays of George Bernard Shaw.
Granville Barker played the poet Eugene Marchbanks is Shaw's Candida and later Napoleon in The Man of Destiny. In 1904, Granville Barker played Keegan in John Bull's Other Island, acting opposite Lillah McCarthy, whom he later married. The two also appeared together the following year in Man and Superman.
Shaw later wrote Fanny's First Play specifically for McCarthy. The show was a hit, running for 622 performances. Clearly, McCarthy was a darling of the box office, but her husband's feelings for her soon cooled. In 1915, Granville Barker left to tour America with some Shakespeare plays he had directed. There, he fell in love with another woman. When he asked his wife for a divorce, it ended his creative relationship not just with her, but with Shaw as well.