Stand-up comedian Ian Cognito has died after reportedly suffering a heart attack while performing on stage in Oxfordshire.
Paramedics were called to the Lone Wolf Comedy Club in Bicester on Thursday at around 10pm, but he was pronounced dead at the scene.
According to reports he had been taking medication for a heart condition.
Comedian and actor Rufus Hound was among several comics who paid tribute to Cognito on social media, saying "we have lost one of the greats".
He tweeted: "Ian Cognito has died.
"That might not mean much to you if your knowledge of stand-up only extends to a screen but for anyone who ever sat down in a comedy club and saw him on a stage - this is a hard one."
Stand-up Luisa Omielan said: "Just heard about Ian Cognito, I saw him one once in stage years ago and was in awe, he was as epic as his reputation. Rebellious and brilliant.
"I heard he passed away after being on stage. He even died like a f****** legend. Far far too soon. Love to his family."
Photographer and friend Craig Smith Jones tweeted an image of Cognito and wrote: "He's gone."
Comedian and author Shappi Khorsandi tweeted: "Ian Cognito dying makes me think of all the wonderful comedians in our community over these 20 years. I love you all. I mean that.
"Time goes by and we don't gig together and i think that eventually we will...and then this happens."
Mitch Benn tweeted that he had known Cognito for 25 years.
He wrote: "Saw him a month ago; looked better than I'd seen him in years. He was 18 months sober and in treatment. This feels so unfair."
The Glee Club in Birmingham tweeted: "We're all very sad to hear of the passing of the legendary Ian Cognito. He was original, always hilarious, sometimes offensive and the true definition of 'one of a kind'. R.I.P Cogs x."
London-born Cognito won the Time Out award for stand-up comedy in 1999.