About Bjorn Ulvaeus:
Björn Kristian Ulvaeus is a Swedish songwriter, producer, a former member of the Swedish musical group ABBA (1972–1982), 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.