Björn Kristian Ulvaeus (born April 25, 1945) is a Swedish musician and composer, most notable as a member of ABBA.
Ulvaeus was born in Gothenburg, but as a child he moved with his family to Västervik.
Prior to gaining international recognition as a member of ABBA, Björn was a member of the Hootenanny Singers. While on the road in 1966, they encountered the Hep Stars, and Björn quickly became friends with the group’s keyboard player, Benny Andersson. While filming a pop special for television in May 1969, Björn met nineteen-year-old Agnetha Fältskog. Benny would then meet Anni-Frid Lyngstad soon after.
After being a member of ABBA he has, together with Benny Andersson, created the musicals Chess, Kristina från Duvemåla (based on the Immigrant novels by Swedish writer Vilhelm Moberg), and Mamma Mia! (based on existing ABBA songs).
Together with Andersson, Ulvaeus was nominated for Drama Desk Award in a category Outstanding Music (for musical Chess) and for Tony Award in a category Best Orchestrations (for musical Mamma Mia). Original Cast recordings of both musicals were nominated for Grammy Award. Ulvaeus also shared with Andersson The Special International Ivor Novello Award from The British Academy of Composers and Songwriters, The Music Export Prize from the Swedish Ministry of Industry and Trade, and Lifetime Achievement Award from the Swedish Music Publishers Association (SMFF).
On July 6, 1971, Björn married Agnetha Fältskog; the marriage resulted in two children Linda (born in 1973), and Christian (born in 1977). In July 1980, Björn and Agnetha divorced, although they both agreed to remain in ABBA. Björn married music journalist Lena Kallersjö on January 6, 1981, and the marriage produced another two daughters, Emma (born in 1982) and Anna (born in 1986).
Ulvaeus and Kallersjö live in Stockholm. From 1984 to 1990 they resided in the UK where Ulvaeus founded an IT-business together with his brother.
Ulvaeus is a member of International Humanist and Ethical Union's Swedish member organisation Humanisterna.