Eddie and the Cruisers
A band that's the subject of not one, but two movies; 1983's Eddie and the Cruisers and 1989's Eddie and the Cruisers II: Eddie Lives! Both featured the music of the otherwise unknown John Cafferty & The Beaver Brown Band.
The Eddie in question was Eddie Wilson (Michael Paré), a way ahead-of-his-time late '50s/early '60s rocker who fakes his own death. The song "On The Dark Side" actually hit #7 on 09/15/1984.