Björn Kristian Ulvaeus is a Swedish musician, singer, songwriter, and producer best known as a member of the musical group ABBA. He is also the co-composer of the musicals Chess, Kristina från Duvemåla, and Mamma Mia! He co-produced the films Mamma Mia! and Mamma Mia! Here We Go Again with fellow ABBA member and close friend Benny Andersson. He is the oldest member of the group.

Mamma Mia! Here We Go Again is a 2018 jukebox musical romantic comedy film written and directed by Ol Parker, from a story by Parker, Catherine Johnson, and Richard Curtis. It is the sequel to the 2008 film Mamma Mia!, which in turn is based on the 1999 musical of the same name using the music of ABBA. The film features an ensemble cast, including Christine Baranski, Pierce Brosnan, Dominic Cooper, Colin Firth, Andy García, Lily James, Amanda Seyfried, Stellan Skarsgård, Julie Walters, Cher, Meryl Streep, Alexa Davies, Jessica Keenan Wynn, Josh Dylan, Jeremy Irvine, and Hugh Skinner. Both a prequel and a sequel, the plot is set after the events of the previous film, and is intersected with flashbacks to Donna's youth in 1979, with some scenes from the two time periods mirroring each other.