Much closer to the current crop of reality contests was the one that came right before Ed Sullivan (7:00 pm Sunday). That was The Original Amateur Hour, hosted (on TV; it started on the radio) by Ted Mack. Here is a list of some who came through that show on their way to stardom.
Frank Sinatra, Gladys Knight, Nick Carter, Pat Boone, Connie Francis, Jim Stafford, Ann-Margret, Robert Klein, Raul Julia, Maria Callas, Beverly Sills, Joey Dee And The Starlighters, The Primettes, with Diana Ross, and Penny Marshall.
Each week was a separate contest. The winner was determined by calls and postcards.