Jonas Petter Berggren was born on March 21, 1967. He started writing songs when he was seven, and continues to write for the Swedish band Ace of Base, as well as other bands. As the founding member of Ace of Base, Jonas has written all of their biggest hits, including All That She Wants, The Sign, and Beautiful Life. He also plays the guitar and keyboards. Working under the artistname of Joker (or, in some later works, JP), Jonas nowadays also has his own studio, The Barn. The female members of Ace of Base, Linn and Jenny Berggren, are his sisters.

He is married to Norwegian Birthe Haugland and together they have two children: Julia, born in 1999, and Gabriel, born in 2001. They currently live in Göteborg, Sweden. Jonas is 6'3" and weighs about 260 pounds (190 cm and 120 kg), and his interests include geography, politics, and playing tennis.