Mark Henry Belanger (June 8, 1944 - October 6, 1998) was an American Major League Baseball player. He was a defensive standout at shortstop, and played all but one year of his career with the Baltimore Orioles. He later became a labor representative for the Major League Baseball Players Association.
Belanger was born in Pittsfield, Massachusetts. He was recruited by the Orioles as an amateur in 1962, and made his debut with the club on August 7, 1965. He took over as the Orioles' regular shortstop in late 1967, and held the position for over a decade.
He was nicknamed "The Blade" because of his height of 6 ft 1 in (1.55 m) and weight of only 170 lb (77 kg), and was known as a poor hitter. In his eighteen seasons in the major leagues, Belanger hit only 20 home runs, and had a lifetime batting average of .228. His true contribution to the team was at his position, where he earned a reputation as one of the best fielding shortstops ever. He earned the American League's Gold Glove Award at shortstop 8 times (1969, 1971, 1973-78), and was named to the American League's All-Star team in 1976. Belanger joined a select list of shortstop-second baseman combinations who each won Gold Gloves in the same season while playing together in 1969 and 1971 with Davey Johnson, and again with Bobby Grich each year between 1973 and 1976 inclusive. His contributions led to the Orioles' World Series victory in 1970, the team's second title in five years.
Belanger was known for his intelligence and his gentlemanly demeanor on and off the field. He was the Orioles' representative in the baseball players' union, the MLBPA, for many years. Playing between star players such as Brooks Robinson and Davey Johnson, he was a favorite of many Baltimore fans, and came to symbolize the Orioles of the 1970s as a group of selfless, determined overachievers whose talents as a team were greater than their sum as individuals.
He was granted free agency in 1981, and signed with the Los Angeles Dodgers for the 1982 season, after which he retired. His successor at the position for the Orioles in 1982 was Cal Ripken, Jr. After his retirement as an active player, he was employed by the MLBPA as a liaison to its membership.
Belanger contracted lung cancer in the late 1990s - perhaps because of his habit of smoking cigarettes - and died in New York City at the age of 54.