Björn Kristian Ulvaeus is a Swedish musician, singer, songwriter, and producer born on April 25, 1945. He was a member of ABBA and is known for co-composing the musicals Chess and Kristina från Duvemåla. Before ABBA, Ulvaeus was a member of the Swedish folk-schlager band Hootenanny Singers. He was also an in-house producer at Polar Record Company, where he met Benny Andersson, his future ABBA partner. Ulvaeus and Andersson worked together and produced records by other artists. He has won numerous awards for his contributions to music, including the prestigious Polar Music Prize.