July 31, 1930 was the first time the voice of The Shadow was heard on the radio. (hat tip to DisContent. Sunset Parker accurately informs us that today is the 76th birthday of the enigmatic voice on the radio, but inaccurately assumes that the Shadow's radio adventures began that same day. In actuality, the Shadow was only a radio host, like the crypt keeper, until September 26, 1937 when (based on the popularity of Walter B. Gibson's -- aka Maxwell Grant -- literary adventures of the Shadow) he was finally given his own radio show.
David Chute, film critic/pulp fan/blogger, has a great article which he wrote for the promotional materials to the Shadow movie.
One must remember when dealing with fictional heroes, in multiple media, that their origins/secret ID's can change. When did Bruce Wayne marry Selena Kyle and what is their daughter's name? Did the Kents take Superman straight home...or to Smallville Orphanage? Hmm...what does Gold Kryptonite do to Supes? Was Hal Jordan an alcoholic or not?
All questions with different answers, depending on the era and medium. Like the Shadow...did he have the power to cloud men's minds...or was he merely using magic tricks?