Teenage cancer fundraiser Stephen Sutton has died peacefully in his sleep, his mother said on his Facebook page.
The 19-year-old, from Burntwood in Staffordshire, raised more than £3.2m ($5.36m) for charity after news of his plight spread on social media.
In a post announcing Stephen's death, Jane Sutton said he was a "courageous, selfless, inspirational son".
Stephen was diagnosed with terminal cancer aged 15.
Rather than dwell on his misfortune, the teenager drew up a "bucket list" of things he wanted to achieve before he died.
This led to him completing a skydive and playing drums in front of 90,000 people before the Uefa Champions League final at Wembley last May, among various achievements.
Ms Sutton said in her statement: "My heart is bursting with pride but breaking with pain for my courageous, selfless, inspirational son.
"The ongoing support and outpouring of love for Stephen will help greatly at this difficult time, in the same way as it helped Stephen throughout his journey.
"We all know he will never be forgotten, his spirit will live on, in all that he achieved and shared with so many."
The Facebook post announcing Stephen's death was shared more than 120,000 times within an hour of its publication.
Donations to his online fundraising page, set up in aid of the Teenage Cancer Trust, began to climb once again as the news of the teenager's death spread.
Justgiving, which hosts Stephen's online fundraising page, said its engineers had to "work quickly" to boost server capacity after a sharp increase in visitors to the site.
It said the campaign total had risen by about £60,000 in just over two hours.
'Credit to humanity'
Stephen was readmitted to hospital on Sunday after developing breathing difficulties caused by the regrowth of tumours.
He had initially set out to raise just £10,000 ($16,800) for charity, but his fundraising campaign attracted huge attention last month after he posted a selfie online.
The image went viral and attracted the support of celebrities including Jason Manford, who championed Stephen's charity efforts.
Paying tribute, the comedian said Stephen "was the most inspiring person I've ever met and touched more lives than he will ever know".
"He was an incredibly positive young man and a credit to his family, to Burntwood and to humanity itself.
"The reason we took to him so passionately was because he was better than us, he did something that none of us could even imagine doing.
"In his darkest hour he selflessly dedicated his final moments to raising millions of pounds for teenagers with cancer."
As well as for his fundraising, Stephen became well known for his bucket list.
Along with skydiving and playing drums to a huge crowd, the list also included hugging an elephant and getting a tattoo.
Stephen, who was diagnosed with metastatic bowel cancer aged 15, was visited earlier this month at Birmingham's Queen Elizabeth Hospital by Prime Minister David Cameron, who praised his "incredible" efforts to help others.
Mr Cameron said: "I can hardly think of anyone I've met with such a zest for life, and such a belief that you can get things done, and who wanted to live every minute.
"He was absolutely inspiring."
Labour leader Ed Miliband also paid tribute and wrote: "Tragic news that Stephen Sutton has passed away. His bravery & determination to live life to the full was an inspiration to us all."
Deputy Prime Minister Nick Clegg wrote: "Very sad to hear about the death of Stephen Sutton. Such a brave, selfless and inspirational young man."
A number of celebrities and public figures have also paid tribute to Stephen.
Comedian Ricky Gervais tweeted: "RIP Stephen Sutton. A true hero & inspiration to us all."
TV presenter Clare Balding tweeted: "Desperately sad to hear that Stephen Sutton has died. I feel privileged to have met him and heard him speak."
The Teenage Cancer Trust, to which Stephen made the largest ever single donation in its history, said: "We are humbled and hugely grateful for what Stephen achieved and continues to achieve for us."
Deborah Alsina, chief executive of Bowel Cancer UK, said Stephen had "undoubtedly created greater awareness... that bowel cancer can affect younger people too and for this we owe him such gratitude".
Staff at his former school, Chase Terrace Technology College in Burntwood, paid tribute to the "model student".
Chair of governors Di Evans said he "made such a difference to people's lives - not just in Burntwood, not just in Birmingham, or England but worldwide".
"He never ever stopped smiling despite that awful illness," she said.
"He never, ever gave up and was fighting to the very end."