Leo John Marentette Jr. (February 18, 1941 – May 8, 2014) was an American professional baseball player and relief pitcher in the Major Leagues who played for the Detroit Tigers (1965) and the Montréal Expos (1969). Listed at 6 feet 2 inches (1.88 metres), 200 pounds (91 kilograms), Marentette batted and threw right-handed. On May 8, 2014, Marentette died of a heart attack at the age of 73 at his home in Lambertville, Michigan.