Marcus Edwin Gwyn (born November 4, 1977) is an American former professional baseball relief pitcher.

After being drafted by the Oakland Athletics in the 2000 Major League Baseball draft, Gwyn made his major league debut on July 29, 2007, for the Los Angeles Angels of Anaheim.

On January 4, 2008, he signed a minor league deal with the Florida Marlins, but was released on July 25, 2008, after spending the entire year with Triple-A Albuquerque.

On July 29, he signed a contract with the Tohoku Rakuten Golden Eagles of Nippon Professional Baseball.

This biographical article relating to an American baseball pitcher born in the 1970s is a stub.