Anni-Frid-Synni "Frida" Lyngstad (born November 15, 1945) is best known as one of the four singers in the pop group ABBA.

Anni-Frid was born illegitimately in Ballangen, near Narvik, Norway as a result of a liaison between Synni - her mother - and a married German sergeant, Alfred Haase, during the German military occupation. Anni-Frid believed that her father had died when his ship to Germany was sunk during the war. After a German magazine published the story of her origins in 1977, Anni-Frid discovered that her father had not died.

At the end of WWII Anni-Frid, her mother and grandmother fled to Sweden for fear of reprisals from the Norwegian population - whose socialist government put many German-fathered children into mental institutions, or sent them overseas. Synni died before Anni-Frid was two, so she was brought up by her grandmother in Eskilstuna, Sweden.

Anni-Frid got her first job as a jazz singer at the age of 13, then formed her own band, the Anni-Frid Four, marrying the bass player Ragnar Fredriksson at age 18, with whom she had two children before divorcing.

In 1967 Anni-Frid won a TV talent contest, and made an album for EMI. She made a second in 1971, produced by Benny Andersson, laying the foundations for ABBA. She married Benny on October 6, 1978 - divorcing in 1981.

In 1992 Anni-Frid married His Highness Prince Heinrich Ruzzo Reuss von Plauen (1950-1999), of the Princely Reuss family.

After the break-up of ABBA in 1982, Frida released a successful album, There's Something Going On, though the follow-up Shine was less popular and proved her last foray into the music world for some years. In 2004 she re-entered the limelight by recording a song, "The Sun will Shine Again", in conjunction with former Deep Purple legend Jon Lord, and also by appearing with Benny and Björn at the London 5th Anniversary performance of the musical based on ABBA songs, Mamma Mia.