Tarjei Bø (born 29 July 1988) is a Norwegian professional biathlete. Bø debuted in the Biathlon World Cup on March 26, 2009 in Khanty-Mansiysk, Russia, and won his first World Cup victory on December 10, 2010. In the 2010 Winter Olympics he earned his first gold medal in the 4 × 7.5 km biathlon relay. On December 10, 2010 he won the sprint race in Hochfilzen, earning his first world cup victory. He also won the following pursuit race and anchored the winning relay team. Bø is the older brother of biathlete Johannes Thingnes Bø.