Manookian was the oldest of three children born to a Christian Armenian family in Istanbul. As a teenager, he survived the Armenian genocide. Manookian immigrated to the United States in 1920. At the age of 16 he studied illustration at the Rhode Island School of Design. Later he took classes at the Art Students League of New York before enlisting in the United States Marine Corps in 1923. While serving in the U. S. Marine Corps he was assigned as a clerk to the author and historian, Major Edwin North McClellan.