Billy Jim Leonard (born 20 March 1946) is an American historian of religion. Bill Leonard was born on 20 March 1946 in Decatur, Texas to a salesman, Marvin R. Leonard, and his wife Lavelle, who worked as a secretary. After he turned ten, Leonard moved with his family to Fort Worth, Texas. Leonard earned a bachelor of arts degree from Texas Wesleyan College in 1968, followed by a Master of Divinity at Southwestern Baptist Theological Seminary in 1971. He then obtained a doctorate at Boston University in 1975. Leonard completed postdoctoral research at Yale University.