Bjorn Ulvaeus is a Swedish musician, songwriter, and producer, best known as a member of the iconic pop group ABBA. Born on April 25, 1945, in Gothenburg, Sweden, he played guitar and contributed to the band's distinctive sound with his songwriting skills. ABBA achieved worldwide fame in the 1970s and 1980s, producing hits like "Dancing Queen" and "Mamma Mia." In addition to his work with ABBA, Ulvaeus has been involved in various musical projects, including the successful stage musical and film adaptation of Mamma Mia!. He has also collaborated with other artists and worked on music for theater, showcasing his versatility in the entertainment industry.