He's been described as a real life superhero, but little Zack Barrett, who touched the hearts of hundreds of people across Yorkshire, has lost his fight against brain cancer.
The six year old from Kirkheaton, who leaves behind twin brother Leo, was only diagnosed last November. He'd been poorly for three weeks and his parents thought he was suffering with a virus. But tests revealed he had a rare and inoperable tumour on his brain stem.
Zack's family and friends immediately started to fundraise, so that they could access experimental treatment to prolong Zack's life. The fund quickly reached more than £43,000.
But Zack's illness, known as Diffuse Pontine Glioma, progresses quickly. He became too ill to have any more treatment and in his final few days, he and his family were cared for by staff at Martin House Hospice.
Zack Barrett passed away yesterday lunchtime, leaving behind his mum, dad and twin brother Leo.
The money raised will now be shared between the charities that helped him and his family, and it will also go towards research into Diffuse Pontine Glioma.
Zack's funeral will be held at 11am on Wednesday the 26th July, at St John's Church in Upper Hopton. His parents have asked everyone to wear black to reflect how sad it it to lose such a young boy.
You can read more about Zack's Fight here.