The cast of Friends have said they are "utterly devastated" by the loss of their fellow star Matthew Perry, who died on Saturday at the age of 54.
In a joint statement, Jennifer Aniston, Courteney Cox, Matt LeBlanc, David Schwimmer and Lisa Kudrow said it was an "unfathomable loss".
The Friends actor was reportedly found unresponsive in a hot tub at his Los Angeles home on Saturday.
Perry's post-mortem examination was inconclusive.
Officials are awaiting the results of toxicology tests.
"We are all so utterly devastated by the loss of Matthew," the Friends cast said in the statement released to the BBC.
"We were more than just castmates. We are a family. There is so much to say, but right now we're going to take a moment to grieve and process this unfathomable loss. In time we will say more, as and when we are able.
"For now, our thoughts and our love are with Matty's family, his friends, and everyone who loved him around the world."
Perry was best known for playing wisecracking Chandler Bing in the hugely popular '90s TV sitcom.
He also appeared in a string of films. Salma Hayek, who starred with Perry in 1997's Fools Rush In, added her tribute.
"There is a special bond that happens when you share dreams with someone, and together you work towards them," she wrote on Instagram, alongside pictures of the pair including one Perry had posted calling their romantic comedy "probably my best movie".
Hayek continued: "Throughout the years, he and I found ourselves reminiscing about that meaningful time in our lives with a deep sense of nostalgia and gratitude.
"My friend, you are gone much too soon, but I will continue to cherish your silliness, your perseverance, and your lovely heart. Farewell, sweet Matthew, we will never forget you."
Perry's former fiancée Molly Hurwitz posted about watching Friends with him as he prepared for the cast's 2021 reunion. "Being with him as he rediscovered his brilliance was magical," she said.
"He would love that the world is talking about how talented he was. And he really was very talented."
'He was complicated'
Hurwitz went on: "But, I obviously knew that man in a very different way, too. While I loved him deeper than I could comprehend, he was complicated, and he caused pain like I'd never known.
"No one in my adult life has had a more profound impact on me than Matthew Langford Perry. I have tremendous gratitude for that, for everything I learned from our relationship."
She also mentioned the "invaluable" Alcoholics Anonymous (AA), before concluding: "I feel relief that you are at peace."
While at the height of his fame, Perry was battling addiction to painkillers and alcohol, and attended rehabilitation clinics on multiple occasions.
In 2016, he told BBC Radio 2 that he could not remember three years of filming during Friends, because of drink and drugs.
More details have emerged about how Perry was discovered on Saturday afternoon in the jacuzzi at his Pacific Palisades home.
The Los Angeles Fire Department said in a statement cited by the LA Times: "An adult male patient was deceased prior to first response arrival.
"The patient was found by a bystander who had re-positioned the victim where the head was out of water.
"Firefighters pulled the victim out of the jacuzzi and did a quick medical assessment to find he was deceased."
Actor Hank Azaria, who appeared in several episodes of the sitcom, playing Phoebe Buffay's boyfriend David, said Perry had been like a "brother" to him.
In a video posted on Instagram, he said: "Matthew was the first friend I made in Los Angeles when I moved there. I was 21 he was 16.
"We did a pilot together... we became really good friends and we were really more like brothers for a long time."
He added: "From a recovery perspective, I mean I'm a sober guy for 17 years. I want to say that the night I went into AA, Matthew brought me in.
"The whole first year I was sober, we went to meetings together and he was such a great... I got to tell him this. As a sober person he was so caring and giving and wise and he totally helped me get sober."
Helping people to recover
Lindsay Posner, who directed the 2016 play The End of Longing, written by and starring Perry, paid tribute to him on BBC Radio 4's Today programme.
"He was always very, very warm and generous, and keen to keep everyone entertained the whole time," he said. "He was very keen to be thought of as a serious actor, a comic actor."
The play was an autobiographical one about addiction. Posner added: "He said to me he would like to be remembered for helping people through the play... helping people to recover."
Kathleen Turner, who played Helena Handbasket, one of Chandler's parents on Friends, told People magazine she was "very sad for Matthew" after learning about his death.
"He had a good sense of humour and a good heart. He liked other people, which, to me, is terribly important, especially for an actor," she added.
Fans gathered outside the Friends apartment building outside New York to leave floral tributes.
"He's had a very impactful role in my life and always has given me tons of laughs, and it's sad to hear about his passing," Taylor Lanthier, 26, told AFP news agency.
"Chandler is a funny guy. He's a loving guy. He's someone who's very dedicated to his friends," she added. "And that's what I think Matthew was as well."
Tributes came in over the weekend from the likes of Gwyneth Paltrow, Friends creators Marta Kauffman and David Crane, and Maggie Wheeler, who played on-screen girlfriend Janice.