Wikipedia describe Supergroups as a rock music group whose performers are already famous from having performed individually or in other groups.

There have been alot of supergroups from 60's onward like Crosby, Stills, Nash & Young, The Firm, Traveling Wilburys, or Damn Yankees just to name few. And some that nobody remember such as Power Station.

Have to say my favorite SP are Traveling Wilburys (George Harrison, Bob Dylan, Tom Petty, Jeff Lynne and Roy Orbison), and The Firm (Paul Rodgers, Jimmy Page). And each group put out two albums before breaking up.



Here is list of Supergroups to refresh memory:

http://en.wikipedia.org/wiki/Supergroup_(music)