Panic! At the Disco is a Las Vegas, Nevada-based pop punk/electronica band and the first major band signed to Fall Out Boy's Pete Wentz's Decaydance label.

The band was formed by guitarist Ryan Ross and drummer Spencer Smith, bassist Brent Wilson and Brendon Urie on vocals. Their name comes from the song "Panic" by Name Taken which was in turn a reference to a song from The Smiths.
(Source: Punknews.org)