Born in Portland, Oregon to Alexander ("El") and Agnes "Sloanie" Nibley, Nibley served in the Navy in New York in 1945 before beginning his career. Nibley served as screenwriter for over twenty films including Springfield Rifle, Carson City, the remake of The Golden Stallion, and Eyes of Texas (1948), a film starring Roy Rogers. He also wrote for numerous TV series, including Sea Hunt, Sky King, Wagon Train, and The Addams Family.