Mark Teahen, American baseball player
Mark Thomas Teahen (born September 6, 1981) is an American-Canadian former professional baseball infielder who played in Major League Baseball (MLB) for the Kansas City Royals, Chicago White Sox, and Toronto Blue Jays.

He graduated from Yucaipa High School in 1999 and attended St. Mary's College in California. Teahen was drafted 39th overall in the 2002 draft by the Oakland Athletics with a sandwich pick between the first and second rounds. He was one of the featured players in the book Moneyball, which claimed that he had the potential to become the next Jason Giambi.

Prior to the 2009 World Baseball Classic, Teahen, whose father was born in St. Marys, Ontario, became a naturalized Canadian citizen and played for Team Canada in that event. In 2011, Teahen and Brett Lawrie both started in the infield for the Blue Jays, marking the first time the squad had two Canadians in its starting lineup.