Göran Bror Benny Andersson was born on December 16, 1946. He is a Swedish musician, composer, member of the Swedish music group ABBA, and co-composer of the musicals Chess, Kristina från Duvemåla, and Mamma Mia!. Benny met Björn Ulvaeus in June 1966, and the two collaborated and wrote songs together, their first song being “Isn’t It Easy To Say”, which was eventually recorded by the Hep Stars. He also had a productive songwriting collaboration with Lasse Berghagen, with whom he wrote several songs and submitted “Hej, Clown” for the 1969 Melodifestivalen – the Swedish Eurovision Song Festival finals and won second place. During this contest, he met vocalist Anni-Frid Lyngstad, and they soon started dating and eventually got married. Around the same time, Bjorn met singer Agnetha Fältskog. The personal relationships and Benny and Bjorn’s songwriting collaboration led to the close co-operation which the four friends had during the following years. Benny and Björn got their first hits as songwriters in the spring of 1969: “Ljuva sextital” (a hit with Brita Borg) and “Speleman” (a hit for the Hep Stars). As the four began supporting each other during recording sessions, the sound of the girls' voices convinced the songwriters to model their ‘group’ on various MOR acts such as Blue Mink, Middle of the Road and Sweet. And so, ABBA came to life.

Source:
​https://en.wikipedia.org/wiki/Benny_Andersson