News of his untimely death spread like wildfire on the Internet and celebrities immediately took to Twitter to share their grief about his passing.
Within minutes, "#RIPCoryMonteith" was trending and Hollywood didn't waste any time chiming in about the unfortunate incident.
Everyone from Kim Kardashian and Taylor Swift to Katharine McPhee and Nina Dobrev are sharing their thoughts on the popular social media site.
Here's a look at what some celebs are saying:
Kim Kardashian: Just heard about the death of Cory Monteith. So sad. Prayers 4 his family. Praying 4 Lea too! Words cant describe what they must be feeling
Taylor Swift: Speechless. And for the worst reason.
Zooey Deschanel: This is such sad news about @CoryMonteith - what an absolutely tragic loss of a very talented young man.
Kaley Cuoco: #CoryMonteith no words. Prayers. Thoughts w his family. This is terrible. Can't speak.
Niall Horan: RIP cory ! Didn't know him personally! Met him on a couple of occasions! Super nice guy! Thoughts and prayers with his family and friends! X
Demi Lovato: #RIPCoryMonteith... So unbelievably tragic. Please #prayforLea..
Kristin Chenoweth: RIP CoryMontieth. You will be loved. Always.
Katharine McPhee: omg. Met this sweet man. RIP.
Kendall Jenner: wow! RIP Cory Monteith. such a nice guy. my thoughts and prayers go out to his family and friends. #RIP
Kylie Jenner: R.I.P pic.twitter.com/oX7T2zAfvX
Julianne Hough: One of the kindest people I've ever met! My heart breaks for Cory's family and loved ones... You will be missed and forever loved Cory!
Olivia Munn: Shocked and saddened by the tragic death of Cory Monteith. All my love to his family, friends & girlfriend. #TooSoon
Kat Dennings: I can't fully process this news. Tragic, tragic loss of a young, promising, talented man. Cory Monteith, rest in peace
Candace Cameron Bure: What?! My heart is sinking
Nina Dobrev: I'm gutted. Shocked and saddened to hear the news, my heart goes out to Cory's family and friends. Lets respect their space as they grieve.
David Boreanaz: R.I.P. Cory Monteith. #Glee.
Rumer Willis: I am truly saddened to hear about Cory Monteith. What a talented and sweet guy. My prayers go out to his family and loved ones.
Sophia Bush: I saw him a few weeks ago in NY, looking so happy. heartbreaking...
Our thoughts go out to all of Cory's family and friends during this incredibly difficult time.