Mark Christian Bellhorn (born August 23, 1974 in Boston, Massachusetts) is a retired Major League Baseball third baseman. He has played in the majors for the Oakland Athletics (1997-1998, 2000-2001), Chicago Cubs (2002-2003), Colorado Rockies (2003), Boston Red Sox (2004-2005), New York Yankees (2005), San Diego Padres (2006), and Cincinnati Reds (2007). He is a switch-hitter and throws right-handed. He graduated from Oviedo High School located in Oviedo, Florida.