The Thirty Seconds to Mars star was devastated to hear about the death of Bennington, who committed suicide on Thursday - and praised the singer for being so intelligent and kind, according to The Hollywood Reporter. A tragic loss of an absolute legend.
"Witnessing his life taught me a lot", Leto, 45, continued. "His laughter, intelligence, kindness and heart". The Linkin Park frontman died on what would have been Cornell's 53rd birthday.
"I dreamt about the Beatles last night".
"You have inspired me in many ways you could never have known".
'I'm still weeping, with sadness, as well as gratitude for having shared some very special moments with you and your lovely family. When I learned it was suicide that had claimed his life, there was little I could do to stop myself from becoming one of those teary-eyed spectacles on public transport.
"I'm sorry, I know meds and/or alcohol may have been involved, I'm just processing like all of us and I know we are all having some of the same thoughts/feelings". You helped me understand that. I'd like to think you were saying goodbye in your own way.
Another posted: "I partly agree and partly disagree but I didn't expect a message this harsh from YOU of all people". I send my love to your wife and children, friends and family. I pray you find peace in the next life.
'With all my love.
The "All the Small Things" hitmakers had been due to share a stage with Linkin Park for their joint "Welcome to Blinkin Park" concerts, but have been left "wrecked" by their friend's death earlier this week and insist it wouldn't be "possible" to perform without "Numb" group. With both men becoming fast friends on the road, they would often team up to duet on each other's songs.
The band's most recent album One More Light was released in May this year. Visit Samaritans.org or call 116 123 (UK) or 116 123 (ROI), 24 hours a day, 365 days a year.