His career began in earnest in 1936 after being signed by a Universal Pictures talent scout while playing Duke Mantee in a summer-stock production of "The Petrified Forest". Wilcox worked in 18 Hollywood films before World War II, starting with the role of the Intern in "Let Them Live". (Another source states that he played the romantic lead in 26 films, before going into the service for World War II.) He was a contract player with Universal Studios, unhappy with his typecasting in "cops and robbers" roles. He is perhaps best known for playing Bob Wayne and his alter ego, "The Copperhead", in the 1940 film serial "Mysterious Doctor Satan".