Dennis DeYoung
Dennis DeYoung (born February 18, 1947) is an American singer, songwriter, musician and producer best known for being a founding member of the rock band Styx as lead vocalist and keyboardist, a tenure that lasted from 1961 until June 1999. DeYoung has been credited as the writer of more Styx songs than any other Styx member, past or present.
source: Wikipedia