His story touched lives across the world, and his love for his football team was heart-warming.
After being diagnosed with neuroblastoma - a rare type of cancer - at only 18-months-old, inspirational 6-year-old Bradley Lowery has died.
His death was confirmed on social media by his parents Gemma and Carl, from County Durham, England.
They wrote: "My brave boy has went with the angels today.
"He was our little superhero and put the biggest fight up but he was needed else where. There are no words to describe how heart broken we are."
A fan of Sunderland, the football club released a statement extending its “love and support” to the family.
Bradley had become their club mascot and developed a friendship with his hero, striker Jermain Defoe. Sunderland said in their statement that the footballer was “heartbroken”.
A minute's applause for the young boy took place just before the kick-off in the club's match against Bury. Some proceeds from the game are being donated to Bradley’s fundraising campaign.
Bradley underwent treatment and was in remission, but relapsed last year.
More than £700,000 was raised by the public in 2016 to pay for specialist treatment for Bradley in New York. Doctors discovered his cancer had spread and the illness had become terminal.
He underwent "tumour-shrinking treatment" at Newcastle's Royal Victoria Infirmary but the cancer continued to spread. It failed.
In May, Bradley was brought home to start palliative care but his health deteriorated further.
Almost exactly a month later, his family wrote on Facebook: "Bradley is deteriorating fast, his temperature is going very high his breathing very fast his oxygen levels low.
"He is sleeping most the time apart from odd times awake. We knew this was coming but we are heartbroken beyond words."
Last week his family posted a picture of Bradley with Defoe. The footballer had signed with another club based in the south of England but returned to the north to visit the child.
On Thursday, Defoe broke down in tears during a press conference for his new club and said the six-year-old would "always be in my heart".
Bradley became known worldwide following an appeal that saw him receive 250,000 Christmas cards from countries as far away as Australia and New Zealand.
In December, he met England manager Gareth Southgate and former football star and pundit Gary Lineker at the BBC Sports Personality of the Year event. He went on to win the programme's goal of the month award after he took a penalty ahead of Sunderland's game against Chelsea.
He also appeared as mascot for the England team at Wembley Stadium before a game that saw Defoe score a goal.
On 30 June a charity single entered the singles chart and all proceeds from the song will go to the Bradley Lowery Foundation, which has been set up in his honour.