A slew of rockers have shared their thoughts on Starr's passing via Twitter. Former Guns N' Roses drummer Steven Adler, who like Starr was an alum of VH1's "Celebrity Rehab," wrote, "R.I.P. Mike Starr!! Such a sad day!"
Velvet Revolver drummer Matt Sorum took the opportunity to send an anti-drug message: "Drugs and alcohol aren't a joke. Please take care of yourself and respect yourself. We lost Mike Starr today. Rest in Peace man."
Mike Portnoy, the former drummer for Dream Theater, echoed the sentiment: "RIP Mike Starr... I watched his struggle on Celebrity Rehab and had my fingers crossed for his recovery... this disease kills... sad stuff."
Mötley Crüe bassist Nikki Sixx, who has struggled with heroin addiction, tweeted: "RIP Mike Starr. Another fallen Soldier to addiction."
Tweeted Lamb of God guitarist Mark Morton: "Horrible news. RIP Mike Starr."
Among the other celebrities sharing their thoughts via Twitter were Dr. Drew Pinsky, who treated Starr on "Celebrity Rehab" and "Sober House." "Devastating to hear of Mike Starr succumbing to his illness," Pinsky wrote. "So very sad. Our prayers are with his family."
"Mike Starr may you RIP," comedian Dane Cook tweeted. "Your music lives on forever."
Pro wrestler/"Dancing with the Stars" contestant Chris Jericho also took an anti-drug stance and referenced Charlie Sheen and the actor's recent hoopla.
"Sorry to hear about Mike Starr's death," he wrote. "Amid all of the joking about tiger blood and winning, let's not forget that drugs kill people."