Wayne never really got used to the name “John Wayne,” and often would not answer when someone called his name. And when he introduced himself, he often said, “My name is John Wayne, but my friends call me Duke.” Indeed, his nickname was Duke – a name he had been given while still a young boy. According to history, he had an Airedale dog named Duke, who would follow him to school. Local firefighters who had befriended the boy, would proclaim “here comes big Duke and little Duke” when they would see the pair walking down the street, and the name stuck. And to clarify a point, his nickname is “Duke,” not “The Duke.” Just Duke.
In fact, Wayne used his real last name and his nickname during his early years in Hollywood, and his first on-screen credit (for 1929’s Words and Music) was as “Duke Morrison.”
According to his birth certificate, John Wayne’s full legal name at birth was Marion Robert Morrison, as evidenced by the birth certificate and accompanying affidavit shown below; as well as his signature on his 1943 application to the Office of Strategic Services (OSS), also shown below.
Although Wayne’s mother may have told him that his name was no longer “Robert,” the fact is, she never legally changed his middle name. From the day he was born until the day his died, John Wayne’s legal name was Marion Robert Morrison. Although Wayne knew this (as evidenced by his OSS application shown above), he still tried to keep the peace with his mother, by using either Michael or Mitchell as his middle name. According to the same OSS application noted above, Which he legally signed as Marion Robert Morrison, Wayne notes that he also uses the name Marion Michael Morrison.
Oh, by the way, I know I mentioned that his first on-screen credit was as Duke Morrison, but did you know that he used (at least once) a name other than Duke Morrison or John Wayne in his on-screen credits? Yep, he sure did. In the 1960 episode of Wagon Train titled The Colter Craven Story, Duke played General William Tecumseh Sherman in a very brief cameo appearance. During his brief time on-screen, he is shown only in shadow. The only recognizable feature being his distinctive voice. The reason for this was simply to give the viewers something of a small mystery – “Was that John Wayne? Was that really John Wayne?” they would ask. And watching the credits roll by at the end of the episode would not answer that question, because he was credited as “Michael Morris.”