25.04.1945 (79 years) (Gothenburg, Västra Götalands län, Sweden)
Björn Kristian Ulvaeus (credited as Björn Ulvæus [ˈbjœːɳ ɵlˈveːɵs]; born 25 April 1945) is a Swedish songwriter, producer, a member of the Swedish musical group ABBA, and co-composer of the musicals Chess, Kristina från Duvemåla, and Mamma Mia!. He co-produced the film Mamma Mia! with fellow ABBA member and close friend Benny Andersson.