Tarjei Bø (born in Stryn on 29 July 1988) is a professional Norwegian 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.
He won the overall 2010/2011 biathlon World Cup. He finished five points ahead of his teammate Emil Hegle Svendsen.
At his first Junior World Championships in 2006 in Presque Isle, Maine, United States, Bø claimed the gold medal in the individual discipline, and the silver medal in the pursuit discipline. A year later in Martell-Val Martello, Italy, Bø again claimed the silver medal in the pursuit discipline, and was part of the Norwegian relay team that won the silver medal. The 2009 Junior World Championships in Canmore, Canada began in disappointment: Bø finished as number 23 in the individual discipline with a total of five shooting errors. However, Bø would eventually claim the bronze medal in both the pursuit and sprint disciplines. During the 2009 European Championships in Ufa, Russia, Bø was the most successful biathlete, and claimed the gold medal in all four races he entered (individual, sprint, pursuit and relay). At the World Cup finals in Khanty Mansiysk, Russia, Bø made his debut in the Biathlon World Cup on March 26, 2009, finishing 61st.
In the 2009–10 season, Bø continued his positive development in the IBU Cup, coming in sixth in the individual discipline and second in the sprint. This led to his appointment to the World Cup races in Pokljuka, Oberhof and Ruhpolding. In Pokljuka, Bø made an impressive performance and finished fourth; in Oberhof, he was part of the Norwegian winning relay team; and in Ruhpolding he was part of the Norwegian relay team that finished second. On January 29, Bø was named as one of the 99 athletes that would travel to the 2010 Winter Olympics in Vancouver, Canada. On February 18, Bø finished 21st in his first Olympics event. Bø was chosen for the Norwegian relay team, that claimed the gold medal before runner-ups Austria and bronze-medalists Russia. At the World Cup stop in Kontiolahti, Finland, Bø ran the last leg for the Norwegian mixed team, securing the win for Norway.
Bø became a regular fixture in the Norwegian team in the 2010–11 season. He started the season with a fourth place in the individual discipline in Östersund, Sweden, followed by a fifth and fourth place in the sprint and pursuit disciplines, respectively. On 5 January 2007, Bø won his first World Cup event, the sprint race in Hochfilzen, Austria, beating runner-up Serguei Sednev by 27.5 seconds. One day later, he won his second World Cup victory in the pursuit discipline. On December 12, he was part of the winning Norwegian relay team. After his highly successful races in Hochfilzen, Bø took the yellow bib of the Overall World Cup leader. In the races in Pokljuka, Bø finished 12th in the individual discipline and second in the sprint. In Oberhof, Bø claimed his third and fourth World Cup victories (mass start and sprint). At the World Cup stops in February in the United States, Bø continued his good form; his worst result was a sixth place. In Presque Isle, Maine, he came in fourth in the sprint discipline. One week later in Fort Kent, Maine, Bø finished all three races in third place (sprint, pursuit and mass start).
On March 3, Bø won his first World Championship title as part of the Norwegian mixed team. Running the last lap, Bø secured Norway the victory; this was the first time Norway had won this event. Two days later, Bø came in third in the sprint discipline, behind runner-up Martin Fourcade and Arnd Peiffer. By finishing third, Bø won the Overall Sprint Cup. In the pursuit discipline Bø again claimed the bronze medal. On March 8, Bø won his first individual gold medal in the individual, beating runner-up Maxim Maksimov by 40 seconds despite having one shooting error compared to Maksimov's clean shooting. Two days later, Bø claimed his second title alongside Ole Einar Bjørndalen, Alexander Os and Emil Hegle Svendsen in the relay, becoming the most successful biathlete at the championships with a total of five medals.
At the season finals in Oslo, Norway Bø, with five shooting errors, came in 44th in the sprint; his second-worst result this season. In the pursuit two days later, Bø started 2 minutes and 15 seconds behind; however, he pulled back the entire time and eventually finished second, 0.6 seconds behind team-mate Emil Hegle Svendsen, thus winning the Overall Pursuit Cup. Bø had a narrow lead of 31 points to Svendsen in the Overall World Cup before the last race of the season, mass start. Svendsen won the event, but as Bø finished eight, he beat Svendsen in the Overall Cup by five points, winning the Overall Cup for the first time in his career.
Bø started the season in poor fashion and finished 25th in the individual in Östersund. He was back on the podium in two of the three next events, however; he finished second in the sprint in Östersund, and came in second in the pursuit in Hochfilzen. He was also part of the winning Norwegian relay team in Hochfilzen, running the last lap.