Five-time world darts champion Eric Bristow has died at the age of 60 after suffering a heart attack.
Professional Darts Corporation chairman Barry Hearn told BBC Sport he collapsed at a Premier League event in Liverpool.
As news of his death reached the crowd at the Echo Arena, fans repeatedly sang: "There's only one Eric Bristow."
Hearn said Bristow, known by his nickname the Crafty Cockney, would "always be a legend in the world of darts and British sport".
World champion five times between 1980 and 1986, Bristow also won five World Masters titles and was a founder player when the PDC was formed in 1993. He was awarded an MBE for his services to sport in 1989.
He also worked as a TV pundit and appeared on ITV show I'm A Celebrity... Get Me Out Of Here in 2012.
In November he lost his role with Sky after suggesting sexual abuse victims were not "proper men".
After more than 20 former footballers made allegations of child sex abuse, Bristow asked on social media why victims did not "sort out" their abusers "when they got older and fitter".
He later apologised for his comments, describing himself as a "bull in a China shop" and said he "appreciated my wording was wrong and offended many people".
"Eric was never afraid of controversy, but he spoke as he found and was honest and straightforward, which is what people admired about him," Hearn added.
"The PDC, and the sport of darts, will miss him."
'Tears for a legend backstage'
Bristow competed at a World Championship for the final time in 2000 - his 23rd in a career during which he won more than 70 professional titles.
He was inducted into the PDC Hall of Fame in 2005 and retired from competing at the end of 2007.
PDC chief executive Matthew Porter posted on social media that he had been with Bristow at Thursday's event in Liverpool before the 60-year-old collapsed.
He wrote: "Awful evening here in Liverpool. Was with Eric earlier and he was in great spirits. A massive character. There are tears for a legend backstage here tonight."
Keith Deller, who beat Bristow to win the 1983 title, said on stage at the Echo Arena on Thursday: "I'm devastated, me and Eric were together all the time.
"What he's done for our game, tonight, if it wasn't for Eric, no-one would be here tonight."
'A maverick, a man of the people'
PDC chairman Barry Hearn, speaking to BBC Sport
It's just unbelievable. He was working as normal in hospitality, started feeling ill and collapsed and died. Our thoughts go out to his family because this has come as a massive shock to the whole sport of darts.
You had players in tears on the Premier League stage tonight and the crowd chanting his name endlessly because of the influence he had on darts. The word legend is overused but it's an understatement for Eric Bristow.
We often talk about the absence of characters in sport but Eric Bristow was a character with a capital 'c'. He was very much a man of the people. He understood what crowds wanted to see - he was controversial, he was a maverick, he spoke his mind and upset a few people from time to time, but the man in the street warmed to him because he was very much one of theirs.
He had time for people, he knew how to entertain, he developed his own style, his own persona and he transcended the sport for 10-15 years and to this day people still remember the Crafty Cockney in his pomp.
He is probably one of the reasons why darts is where it is today - it hasn't lost that touch with the ordinary man, because it is made up of ordinary men with extraordinary ability, and Bristow was the ringleader from the beginning. His name is synonymous with darts.
Eric Bristow and Phil Taylor are the two legendary names from that era that took the sport out of the pubs and onto the global stage.
It has come out from the ordinary working man's game and Eric Bristow epitomised where the game came from but had the star quality to take it to the next level. For that, every player playing today should be grateful, because he blazed a trail.
I think Eric deserves to be remembered and we'll discuss how but at the moment we're just shocked by a great player and great personality leaving us far too early at age of 60.
'Funny, forthright, he will be missed'
Two-time world champion Michael van Gerwen on BBC Radio Merseyside: "It's a huge shock. He's a legend in what he did. Look at what he did for darts, how many titles he won.
"He was someone with very honest opinions. He's going to be a big miss. He was one of the makers of darts, great for the sport. He was still working always and never gave up and to hear of this - I know him quite well - I have goosebumps all over my body at the moment.
"I just heard the news straight after my game, no-one ever saw this coming. My thoughts are with his family who must be going through a horrible time right now."
Sixteen-time world champion Phil Taylor, who was mentored by Bristow, wrote on Twitter: "Words cannot express how sad and shocked I am to hear the terrible news about Eric's passing. A huge influence on my career and a larger than life character, the world has lost a legend. RIP pal."
Two-time world champion Dennis Priestley also wrote on Twitter: "Absolutely devastated to be told earlier that my good friend Eric Bristow has passed away. We shared some great times together and I'm so saddened that we won't get to share anymore. Rest in peace old friend."
Five-time world champion Raymond van Barneveld: "I am lost for words and really devastated! He was darts. He meant so much to me, I cannot believe it. My thoughts go out to his wife and family."
Two-time World Championship runner-up Simon Whitlock: "Shocked and saddened to hear the news about a true legend of the sport I love. RIP Eric Bristow. Thanks for everything you did for darts."
Former Doctor Who star Colin Baker, who appeared with Bristow in I'm A Celebrity Get Me Out Of Here: "So very sad to hear about Eric Bristow tonight. He kept me sane and focused in I'm A Celeb and was a funny, forthright, no-nonsense friend. My thoughts are with his family. I'll miss him."
Kevin Painter, PDC World Championship runner-up in 2004: "Devastated to hear the news that my great pal and darting legend Eric Bristow has passed away, RIP my friend."
Former world heavyweight boxing champion Frank Bruno: "Very saddened to hear the news that Eric Bristow has passed away today, God rest his soul. RIP."
Ex-heavyweight world boxing champion David Haye, who appeared with Bristow in I'm A Celebrity... Get Me Out Of Here in 2012: "So sad to hear darts legend and great guy Eric Bristow passed away. I was fortunate to spend three weeks as his camp mate living in the jungle. Even on the toughest of days his dry sense of humour and quick wit truly made the trip memorable. A real gent, he'll be missed by many. RIP.