Bradley Lowery's parents have confirmed the six-year-old has died following a long battle with neuroblastoma -- a rare type of cancer.
Sunderland supporter Lowery came to the attention of many football fans because of his friendship with former Black Cats striker Jermain Defoe.
He went on to become a mascot for Sunderland in the Premier League and England in a World Cup qualifying game against Lithuania and found a place in the hearts of thousands of football fans around the world with supporters of different clubs making banners and chanting his name at matches. Bradley also won Match of the Day's goal of the month competition in January 2017.
A statement on his official Facebook page, written by his mother Gemma, said: "My brave boy has went with the angels today 07/07/17 at 13:35, in mammy and daddies arms surrounded by his family.
"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.
"Thank you everyone for all your support and kind words.
"Sleep tight baby boy and fly high with them angels".
Sleep tight little one... �� pic.twitter.com/iGqLXdvlVi
- Jermain Defoe (@IAmJermainDefoe) July 8, 2017
Bradley and Defoe were pictured snuggled up together at the youngster's home in Blackhall, County Durham last week after the little boy had a party in bed.
As Bradley continued to fight for his life, Defoe broke down in tears on Thursday at a news conference with his new club, Bournemouth, when he was asked about their special bond.
"He's obviously struggling. I can say it's a matter of days," Defoe said in quotes reported by BBC Sport. "It's been hard because I have kept this in for so long.
"I speak to the family every day. I was with him a few days ago and it was tough to see him suffer like that.
"He will always be in my heart for the rest of my life. There isn't a day that goes past when I don't wake up and check my phone or think about little Bradley. His love is genuine and I can see it in his eyes when he looks at me."
Sunderland also posted a statement on the club's official website that read, in part:
"Our thoughts and prayers are with Bradley's parents, Gemma and Carl, his brother Kieran and their family and friends. We extend our love and support to them, now and always.
"Bradley captured the hearts and minds of everyone at our club with his indomitable spirit, tremendous courage and beautiful smile, which could light up even the darkest of rooms. Despite battling neuroblastoma for much of his all too short life, he demonstrated a bravery and fortitude beyond his years that humbled us all. He was truly an inspiration."
Supporters had hoped a massive fundraising effort last year could get him to the US for pioneering treatment, but his heartbroken family announced at Christmas that his cancer was terminal.
They kept his many well-wishers around the world up to date by using social media and in his final days, his mother, Gemma, revealed that Bradley's health was deteriorating quickly.
Information from the Press Association was used in this report.