Mark Cwiertnia (born 11 January 1984), better known by the artistic name Mark Forster, is a German singer. In 2015, he became the vocalist of a duo cooperation, a musical project named Eff in association with DJ and music producer Felix Jaehn.
Mark Forster is of mixed German and Polish origins. He was born to a German father. His mother was Polish named Agnieszka Cwiertnia originating from Warsaw.His mother called him Marek and in his early days as a musician used the name Marek Cwiertnia. He grew up in Winnweiler, Kaiserslautern (Rheinland-Pfalz).
He later moved to Berlin where he developed a career as a singer, songwriter, pianist and composer of jingles for television including for the show Krömer – Die Internationale Show. From 2007 to 2010, he accompanied actor and comedian Kurt Krömer as a pianist sidekick.