His Cherokee nickname was given to him by his father for the clu-clu birds (known in English as martins, like his middle name) that were nesting at the Gulager home at the time of his birth. From 1946 to 1948, Gulager served in the United States Marine Corps. After attending Northeastern State University in Tahlequah, Oklahoma, Gulager transferred to Baptist-affiliated Baylor University in Waco, Texas. He won a 1-year scholarship to study abroad, where he worked under Jean Louis Barrault, an internationally known French actor and director. In 1952, he returned to Baylor. In 1960, he married fellow actor Miriam Byrd Nethery, an Arkansan. The couple had two sons, including film director John Gulager, and remained married until her death in 2003.