Gregory Walcott grew up in North Carolina and went into the Army just after the end of World War II. After leaving the service, he grew restless on the East Coast and, with $100 in his pocket, thumbed his way west to pursue an acting career. An agent who spotted him in a little theater play helped Walcott land his debut movie role in Duel dans la forêt (1952). Two years later, on the strength of his performance as a drill instructor in the Marine Corps movie Le cri de la victoire (1955), he was placed under contract at Warner Brothers. He co-starred (as a drill instructor again) in another Marine Corps story, Le héros d'Iwo-Jima (1961), which earned him a Universal contract and his own TV series, 87th Precinct (1961) (1961-62) with Robert Lansing.
