Benny Andersson (b. December 16, 1946, Sweden) and Bjorn Ulvaeus (b. April 25, 1945, Sweden) were both members of a late-'60s Swedish pop group called the Hep Stars. Leaving that group, they formed a duo, Benny and Bjorn, and released one album, Lycka, in 1970. They then teamed with Agnetha Faltskog and Anni-Frid Lyngstad to form ABBA, which became one of the most successful pop groups of the 1970s. After ABBA broke up in 1982, Andersson and Ulvaeus collaborated with British lyricist Tim Rice to write the concept album/stage musical Chess. ~ William Ruhlmann, Rovi