Sixteen-year-old boxing champion James Puzey, from Whitland, Carmarthenshire, died in a motorbike crash in Carmarthen in August.
"
James was such a caring kid and I'm sure this is what he would have wanted
"
John Puzey, Grandfather
But the tragedy has helped save several other lives.
James' heart has been given to a 37-year-old mother, while his kidneys have been donated to an 11-year-old boy and a 57-year-old grandmother.
His grandfather John Puzey, 64, descibed James - who was known as Jammo - as "a true champion".
"It was tough losing him but we have taken a great deal of comfort that he has given fresh hope and life to so many people," he said.
"It means that James's death was not in vain.
"We hope that the people who have benefited will also see him as their champion too.
"The young mother who now has his heart will be able to see her little baby grow up," he added.
"The 11-year-old lad has now got a bright future - he had been waiting in hospital for months for a suitable match.
"After the transplant he was out of hospital in eight days - now he has his whole life to look forward to.
"James was such a caring kid and I'm sure this is what he would have wanted."
Tribute
James, who had a brother and two sisters, had been Welsh schoolboy boxing champion at the age of 14 and went on to secure the British title.
After the accident in Carmarthen town centre, he was in a coma for nine days before his life support machine was turned off.
"
It would have been a hell of a waste if his organs had not been used to help others
"
Mike Haines, Grandfather
In three other transplants, his eyes were given to two men - a 71-year-old and a 27-year-old - and his liver was donated to a woman, aged 34, although she died after the operation.
James, who was buried with photographs of his family, had lived with his other grandfather Mike Haines.
Mr Haines also paid tribute to his grandson.
"He was a really fit young man and it would have been a hell of a waste if his organs had not been used to help others," he said.
"He was very popular with friends all over the place.
"He told them if he ever died that he wanted pictures of his family buried with him because he did not want to travel alone," he added.