cast of rock heavyweights crammed the Roxy stage in Hollywood Thursday night (May 1) for a jam session that found the likes of Jane's Addiction's Dave Navarro, Sugar Ray's Mark McGrath and Matt Sorum (Velvet Revolver, Guns N' Roses) on stage with the likes of Lemmy Kilmister of Motorhead, Steve Jones and Paul Cook of the Sex Pistols and Alice In Chains' Jerry Cantrell.

All came together for the first of five Thursday-night gigs in May featuring Navarro and Sorum's occasional side project, Camp Freddy, which also features guitarist/vocalist Billy Morrison, bassist Chris Chaney (Jane's Addiction, Alanis Morissette) and singers McGrath and Donovan Leitch, son of folk singer Donovan.

The Roxy is known for holding occasional jam sessions with top-shelf names, and this collective opened its Roxy stand by wowing the crowd with covers of songs by Thin Lizzy ("Jailbreak"), Oasis ("Rock and Roll Star"), Killing Joke ("Eighties"), Blur ("Song 2") and David Bowie ("Suffragette City").

"I don't know what you think of me, because I've done some pretty douche-y things in my life. But that's okay, because right now I'm gonna do the greatest thing in my life," McGrath said in introducing Jones and Cook for a rendition of the Pistols' "EMI," featuring Sorum on backing vocals. "Live it, love it, blog about it," he added before taking lead vocals.

Motorhead's Kilmister got the biggest roar of the night, joining the ensemble for his band's "Ace of Spades," which found the likes of Extreme/Satellite Party's Nuno Bettencourt bouncing in the audience. Billy Duffy of the Cult and Sean Kinney of Alice In Chains also watched in approval.

Ex-Ratt guitarist Warren DiMartini joined up for "Suffragette City" and a take on his band's "Round on Round," which provoked another roar when he and Navarro synched up on the track's dueling guitar solo. Guitarist Cantrell, a last-minute addition, took the stage for "Jailbreak," and singer-songwriter Poe led the band through Led Zeppelin's "Good Times Bad Times."

The gig at times found multiple bassists (Kilmister, Chaney and Corey Parks, formerly of Nashville Pussy), multiple drummers (Sorum, Cook, Stephen Perkins of Jane's Addiction) and multiple guitarists (Bettencourt, Jones, Navarro, Morisson) all playing together, as they did on the closer: the Stooges' "I Wanna Be Your Dog."