Mark Henry Belanger (June 8, 1944 – October 6, 1998), nicknamed "the Blade," was an American professional baseball player and coach.

In defensive Wins Above Replacement (WAR), Belanger is tied with Ozzie Smith and Joe Tinker for most times as league leader with six.

Belanger took over as the Orioles' regular shortstop in late 1967 from future hall of famer Luis Aparicio,[3][5] and held the position for more than a decade.

Despite his famously poor hitting, Belanger had substantial success against some of the best pitchers of his era, including Bert Blyleven, Nolan Ryan and Tommy John.

Belanger joined a select group 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).

Because Brooks Robinson won the AL Gold Glove at third base each season during the 1960–1975 stretch, the left side of the Orioles' infield was seemingly impenetrable.

He hit a rare home run in the first American League Championship Series game ever played in 1969.

After uncharacteristically hitting .333 in the 1970 ALCS, his contributions led to the Orioles' 1970 World Series victory, the team's second title in five years.

[5] On June 3, 1977, Belanger was part of what sportswriter Fred Rothenberg called "one of the strangest triple plays in baseball history."

With the bases loaded for the Royals in the ninth inning, and Kansas City down 7–5, John Wathan hit a fly ball to right field that Pat Kelly caught for the first out.

[3] Belanger and his first wife, Daryl (Dee), had two homes—in Timonium, Maryland and Key Biscayne, Florida—and had two sons, Richard and Robert.

[3] A long-time cigarette smoker, Belanger was diagnosed with lung cancer in the late 1990s and died in New York City at the age of 54.