Samuel Doyle Riddle (July 1, 1861 – January 8, 1951) was an American businessman and racehorse owner. He was born in Glen Riddle, Pennsylvania, a small town southwest of Philadelphia given the family name by his father.Samuel D. Riddle, a native of Delaware County, owned and operated a woolen mill started by his father, but is best known as a sportsman. His father Samuel Riddle was born in Ireland and arrived in America in 1825. His mother was Lydia Doyle. He had a brother, Leander W. Riddle.