William Martyn-Green (22 April 1899 – 8 February 1975), better known as Martyn Green, was an English actor and singer. He is best known for his work as principal comedian in the Gilbert & Sullivan comic operas, which he performed and recorded with the D'Oyly Carte Opera Company and other troupes.
After army service in World War I, Green studied singing and began to perform in musical theatre. In 1922, he joined the D'Oyly Carte Opera Company playing in the chorus and in a variety of smaller roles, while understudying, and often substituting for, the company's principal comedian. Beginning in 1931, he was regularly given the roles of Major-General Stanley in The Pirates of Penzance and Robin Oakapple in Ruddigore. In 1934, Green became the principal comedian, playing all the famous Gilbert and Sullivan patter roles, including Sir Joseph in H.M.S. Pinafore, the Major-General in Pirates, Bunthorne in Patience, the Lord Chancellor in Iolanthe, Ko-Ko in The Mikado, Jack Point in The Yeomen of the Guard and the Duke of Plaza Toro in The Gondoliers, among others.
At the beginning of World War II, Green left the D'Oyly Carte organisation and acted in other companies. In 1941, he joined the Royal Air Force, serving until 1945. He soon rejoined D'Oyly Carte and continued as the principal comedian until 1951. He then left the company again and moved to New York City, where he continued his career in Broadway musicals, plays, television, recordings and films. In 1959, his left leg was crushed in a garage elevator and had to be amputated below the knee. Greatly determined, Green was soon acting and directing again using a prosthetic limb. He continued to act and direct for the rest of his life and had film roles in A Lovely Way to Die (1968) and The Iceman Cometh (1973).