News of Cory Monteith's (Finn) death shocked us all late Saturday night. After successfully completing a month in rehab for substance abuse this April, the Glee star appeared to be doing well. He and girlfriend Lea Michele (Rachel) were spotted out in public many times, and Cory's life seemed to be getting back to normal. Then on Saturday, July 13, police confirmed that Cory has died in a hotel in Vancouver, BC.

Celebrities have flocked to Twitter to express their shock and horror over this tragic event, and not just Glee stars, either. Here's a look at what costars and other celebs are saying.

For all the latest news and updates on Cory Monteith’s death, click here.