Starting out as a child actor in 1915, Ben Alexander's first roles were in the films of such directors as Cecil B. DeMille and D.W. Griffith. He later graduated to juvenile leads and supporting parts in sound films, most notably in À l'ouest rien de nouveau (1930). When his acting career slowed down in the mid-'30s, he found a new career as a successful radio announcer. Alexander was more or less retired when producer Jack Webb picked him for the part of his detective partner in the TV series Badge 714 (1951). Alexander later played another detective on Howard Duff's TV series Brigade criminelle (1966).
