George Clooney 'Knew' Matthew Perry 'Wasn’t Happy' on 'Friends' But 'Had no Idea' Late Actor 'Was Doing 12 Vicodin a Day'

George Clooney was aware of Matthew Perry's struggles more than 20 years ago, though he didn’t know just how bad things were for the fellow A-list actor until recently.

In a new interview published Tuesday, December 19, the Ocean's Eleven star reflected on his decades-long friendship with Perry — whom he bonded with while they were working on their respective NBC shows, both of which premiered in 1994.

"He was a kid and all he would say to us, I mean me, Richard Kind and Grant Heslov, was, 'I just want to get on a sitcom, man. I just want to get on a regular sitcom and I would be the happiest man on Earth,'" Clooney, who starred on ER from 1994 until he left the main cast in 1999, later making a few guest appearances, said.

"And he got on probably one of the best ever," the 62-year-old admitted, however, "he wasn’t happy."

"It didn’t bring him joy or happiness or peace," Clooney continued, admitting he didn’t know the extent of "what was going through him” despite working "side by side on the soundstage" for so many years.

It wasn’t until the Batman & Robin star read Perry’s memoir, Friends, Lovers and the Big Terrible Thing, when Clooney learned the hard truth about Perry’s addiction battle.

"We just knew that he wasn’t happy and I had no idea he was doing what, 12 Vicodin a day and all the stuff he talked about, all that heartbreaking stuff," he confessed. "It also just tells you that success and money and all those things, it doesn’t just automatically bring you happiness. You have to be happy with yourself and your life."

While their friendship blossomed during their time as NBC actors, Clooney’s relationship with Perry dates back even further.

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"I knew Matt when he was 16 years old," Clooney shared of Perry — who devastatingly died from the "acute effects of ketamine" on Saturday, October 28, at age 54. "We used to play paddle tennis together. He's about 10 years younger than me."

"He was a great, funny, funny, funny kid," the dad-of-two sorrowfully concluded of the late sitcom star.

Fans, friends and family were devastated to hear of Perry’s passing at the end of October, when his assistant found him drowned in his backyard hot tub before calling the police.

"Contributing factors in Mr. Perry's death include drowning, coronary artery disease and the effects of buprenorphine (used to treat opioid use disorder). The manner of death is accident," the Los Angeles County Medical Examiner's Office further detailed in the 17 Again actor's autopsy report.

Deadline spoke to Clooney about Perry while promoting his new film The Boys in the Boat.