Brave little 'Batman' Ben Farrell has passed away before he could undergo a potentially life-saving cancer treatment in the US.
The five-year-old, who won the hearts of people throughout Ireland, was surrounded by his family in Dublin when he died.
He was diagnosed with a rare form of cancer on Christmas Eve last year.
Doctors told Ben's mum Valerie that he had a tumour, and it would more than likely turn out to be cancerous.
"Never in a million years could I have imagined they would say that. It was the most devastating news. We were in shock. It couldn't be real. It didn't make sense," she said.
He had a stage IV Wilms tumour, which doctors in Ireland had struggled to treat, including with 19 rounds of radiotherapy.
Several fundraising events were organised to help pay for pioneering treatment in the US for the little boy from Finglas.
Many people contributed to the campaigns to help the little "superhero'" His family hoped Ben could be saved by taking part in a clinical trial at a US hospital that would cost an estimated €260,000.
The family arrived in the US four weeks ago, knowing Ben had progressive tumours.
Doctors at Our Lady's Hospital for Sick Children in Crumlin in Dublin had said their options had been running out.
Valerie, when seeking funding, said her little boy was facing a battle no child should ever have to face. However, despite it all he kept smiling and continued to wear the beloved Batman mask that earned him his nickname.
"He does it all while remaining happy and singing and cracking up the nurses," she said at the time.
His family said doctors explored every alternative option to save his life.
Doctors contacted experts in the US and Europe, but nothing had been proven to work. Clinical trials for Ben's cancer in the US had shown promising results in laboratory tests.
The family launched a Go Fund Me page to help raise €192,000 for the treatment, which was due at the Children's Hospital in Washington.
The family's ordeal began when Ben began complaining of a sore tummy.
"We thought he just had a bug or it was an excuse for him to sleep in our bed," his mum said. "His pain wasn't excruciating, and it would come and go."
Ben's family wrote on the official Facebook page last night: "Our beautiful Ben has fought the hardest of battles, he was surrounded by love everyday of his life, and this morning was no different. He has done us proud every step of the way ... now we must do him proud.
"Ben's smile, his character, his living at 100mph and his endless love for EVERYONE he has ever met leaves a legacy of gigantic proportions.
"They say if you can leave this world a little better than you found it you have truly lived, in only five short years he accomplished this. We would love to hear your Ben stories and see your Ben pictures ... "