Petter Northug Jr. is a Norwegian former cross-country skier and double Olympic champion. He won a total of 13 World Championship and two Winter Olympic gold medals with 20 medals overall, and 18 individual FIS Cross-Country World Cup wins with 13 podium places. He is also the record holder for most stage wins (13) in Tour de Ski. By winning his ninth gold medal in the Nordic World Ski Championships in 4 × 10 km relay in Val di Fiemme 2013 he leveled the achievement of Bjørn Dæhlie who had been the most successful World Champion male skier up to that point. He is considered by many as the greatest cross country skier of all time.

The FIS Nordic World Ski Championships is a biennial Nordic skiing event organized by the International Ski Federation (FIS). The World Championships was started in 1925 for men and opened for women's participation in 1954. World Championship events include Nordic skiing's three disciplines: cross-country skiing, ski jumping, and Nordic combined. From 1924 to 1939, the World Championships were held every year, including the Winter Olympics. After World War II, the World Championships were held every four years from 1950 to 1982. Since 1985, the World Championships have been held in odd-numbered years.