Jonas Petter Berggren is a Swedish musician, singer-songwriter, and record producer, also known as Joker. He started writing songs when he was seven and continues to write for the band Ace of Base, a group he formed with his two sisters Linn and Jenny. Berggren has written most of their hit songs including "All That She Wants", "The Sign", and "Beautiful Life". As well as singing, he also plays the guitar and keyboards.