Dennis Patrick Leonard (born May 8, 1951) was a pitcher for the Kansas City Royals in the late '70s and early '80s. He retired in 1986 due to injuries.
Born in Brooklyn, Leonard attended Oceanside High School on Long Island, then played college baseball for and graduated from Iona College. In 1975, his first full year with the Royals, he achieved a 15-7 record. He later recorded three 20 win seasons. He started 9 post-season games for the Royals between 1976 and 1981, ending with a record of 3-5, including a 1-1 record in the 1980 World Series against the Philadelphia Phillies.
Towards the end of his career he missed most of the remaining seasons due to knee injuries. His final season was in 1986 where he ended up with an 8-13 record. Besides his rookie season of 1974 this was the only time he had a losing record. At the end of the 1986 season he retired as a player.