Dennis Leonard is a former professional baseball player who had a successful career as a right-handed pitcher in Major League Baseball (MLB). He spent his entire 12-year career with the Kansas City Royals, from his debut in 1974 until his retirement in 1986.

Leonard was known for his powerful fastball and his ability to pitch deep into games. He was a workhorse for the Royals, consistently ranking among the league leaders in complete games and innings pitched. He was one of the most dominant pitchers in the American League during the late 1970s and early 1980s.

Leonard's career was marked by several standout seasons. In 1977, he won 20 games for the first time, a feat he would repeat in 1978 and 1980. He led the American League in complete games in 1977 and 1978, and in wins in 1977. He was also a key contributor to the Royals' postseason success, helping the team reach the playoffs five times and the World Series twice.

Despite his success, Leonard's career was also marked by adversity. In 1983, he suffered a severe knee injury that required multiple surgeries and kept him out of baseball for nearly two years. He made a remarkable comeback in 1986, winning eight games and earning the American League's Comeback Player of the Year award. However, his comeback was short-lived, as he retired after the 1986 season due to persistent knee problems.

Leonard finished his career with a record of 144 wins and 106 losses, a 3.70 earned run average, and 1,323 strikeouts. He ranks among the Royals' all-time leaders in several pitching categories, including wins, complete games, and strikeouts. Despite his impressive career, Leonard has not been inducted into the Baseball Hall of Fame.

Off the field, Leonard was known for his quiet demeanor and his dedication to the Kansas City community. He has remained involved in the Royals organization and the Kansas City area since his retirement, working in various roles and participating in numerous charitable activities.