Chicago consists of Peter Cetera.
Chicago is a rock band that was formed in 1967 in Chicago, Illinois. Well known for being one of the first (and, indeed, one of the few) rock bands to make extensive use of horns, Chicago started as a politically-charged, sometimes experimental rock band and later moved to a softer sound and became famous for producing a number of hit ballads. They had a steady stream of hits throughout the 1970s and 1980s.
The band was formed when a group of DePaul University music students began playing a series of late-night jams at clubs on and off campus.