William Leonard Tremel (July 4, 1929 – December 22, 2013) was a American professional baseball player, a right-handed relief pitcher who appeared in parts of three Major League Baseball seasons for the 1954–1956 Chicago Cubs. Nicknamed "Mumbles," Tremel batted right-handed, stood 5 feet 11 inches (1.80 m) tall and weighed 180 pounds (82 kg).