Marc Kroon is a former professional baseball player who played as a relief pitcher in Major League Baseball (MLB) and in various international leagues. He was born on April 2, 1973, in Bronx, New York, and attended Lehman High School in the Bronx.

Kroon was drafted by the New York Mets in the 1991 MLB draft and made his professional debut in 1995. He spent several years in the Mets' minor league system before making his MLB debut in 1999. Kroon played for the Mets for two seasons, appearing in 32 games and posting a 5.08 ERA.

After leaving the Mets, Kroon played for several other MLB teams, including the San Diego Padres, Colorado Rockies, and Yokohama BayStars in Japan. He also played in various minor leagues and independent leagues in the United States.

Kroon's most successful years were in Japan, where he played for the Yokohama BayStars from 2005 to 2011. He was a dominant closer for the team, recording 177 saves and a 2.19 ERA during his time there. He was also named to the Nippon Professional Baseball (NPB) All-Star team four times and won the NPB championship with the BayStars in 2010.

Kroon retired from professional baseball in 2012 at the age of 39. He finished his career with a 5.08 ERA in 68 MLB games and a 2.19 ERA in 381 NPB games. He also played in various other international leagues, including the Mexican Pacific League and the Chinese Professional Baseball League.

Off the field, Kroon has been open about his struggles with addiction and has spoken publicly about his journey to recovery. He has also worked as a coach and mentor for young baseball players, including his own son, who is also a pitcher.

In summary, Marc Kroon was a relief pitcher who played in MLB and various international leagues. He had a successful career in Japan, where he was a dominant closer for the Yokohama BayStars and won the NPB championship in 2010. Kroon has been open about his struggles with addiction and has worked as a coach and mentor for young baseball players.