Ulf Leo Sommer (born August 26, 1970 in Jena) is a German music producer and composer. He is best known for his work on the complete works of the duo Rosenstolz. His compositions and productions of hits for Rosenstolz, No Angels, 2Raumwohnung, Sarah Connor, Helene Fischer and the Bibi&Tina soundtracks make him one of the most successful German songwriters and producers today.