Rosenborg Ballklub, commonly referred to simply as Rosenborg (Urban East Norwegian: [ˈrùːsn̩bɔrɡ]) or RBK, is a Norwegian professional football club from Trondheim that plays in Eliteserien. The club have won a record 26 leagues titles, a shared record 12 Norwegian Football Cup titles and have played more UEFA matches than any other Norwegian team. RBK play their home games at the all-seater Lerkendal Stadion which has a capacity of 21,421.

The club was founded as Odd in 1917 but were not allowed to play amateur league matches until 1928, when they took the present name. They reached the League of Norway in 1937–38, but were relegated to lower divisions during the 1940s. The club moved to Lerkendal in 1957 and their first title was the 1960 Cup, resulting in their first participation in a UEFA tournament. It was not until the 1960s that RBK was established as Trondheim's leading football team. In 1967 RBK was promoted to the top league where they, except for the 1978 season, have remained ever since. They won three league titles between 1967 and 1971. The club's golden era started with the 1985 league title. From 1991 through 2004 the team won 13 consecutive titles, 10 under manager Nils Arne Eggen. During this period, they also participated in the group stage of Champions League 11 times, reaching the quarter-finals in 1996–97.