Former Scotland rugby international Doddie Weir has died aged 52 after suffering with motor neurone disease.
Weir, who won 61 caps in a legendary Scotland career, used his profile to push for better research to be carried out into MND following his diagnosis in 2016, and appealed for improved care to be given to those afflicted.
"It is with great sadness that we announce the death of our beloved husband and father, Doddie," read a statement from the family via the Scottish Rugby Union.
"Doddie was an inspirational force of nature. His unending energy and drive, and his strength of character powered him through his rugby and business careers and, we believe, enabled him to fight the effects of MND for so many years.
"Doddie put the same energy and even more love and fun into our lives together: he was a true family man. It is difficult to put into words how much we will miss him.
"MND took so much from Doddie, but never his spirit and determination. He battled MND so bravely, and whilst his own battle may be over, his fight continues through his foundation, until a cure is found for all those with this devastating disease."
In 2019 Weir was awarded an OBE for services to rugby, motor neurone disease research and the Scottish Borders community.
A towering lock and lineout specialist, Edinburgh-born Weir scored four tries during his 10-year (1990-2000) Scotland career and helped his country to the 1999 Five Nations Championship - Scotland's last major tournament success. He was also part of the British and Irish Lions squad which toured South Africa in 1997, although his trip was cut short due to injury.
Having moved to Newcastle, Weir won the 1997-1998 Premiership title, before ending his playing days with Border Reivers.
Although his battle with MND gradually took its toll, Weir continued his fundraising campaign and set up the 'My Name'5 Doddie' foundation.
Kevin Sinfield, the Leeds Rhinos great and Leicester Tigers defence coach who - inspired by close friend Rob Burrow as well as Weir and ex-Bradford City captain Stephen Darby - fundraised for MND said: "Today is a deeply sad day for everyone who knew Doddie but especially his family, who are at the forefront of our thoughts.
"Doddie was a giant as a player but his campaigning following his MND diagnosis made him a colossus.
"When Bryan Redpath first put me in touch with Doddie to speak to Rob Burrow following Rob's own diagnosis, he immediately said yes without hesitation. The sight of 5'4" Rob and 6'6" Doddie was something that will live with all of us and probably bonded the duo with the great humour they shared. Doddie was able to give Rob the greatest gift of hope that night. He has been like a big brother to all of us since that day.
"I am honoured to have been able to call Doddie my friend and I know his spirit lives on in all of us who knew him. He will always be a champion."
Newcastle paid tribute to "lifetime friend" Weir in a club statement.
"Following his diagnosis of motor neurone disease in 2017 Doddie showed his characteristic mixture of determination and good humour in raising many millions for research into the currently-incurable condition," Newcastle said.
"It was our honour to display his foundation's logo on the front of our shirts when we played at St James' Park in front of a club record crowd of more than 30,000 in 2018, and to play our part in supporting their incredible fundraising activity.
"All associated with Newcastle Falcons would like to express our sadness at hearing the news of Doddie's passing, whilst at the same time remembering the many happy memories and good times of which he was a central part."
Jill Douglas, chief executive of Weir's foundation, said: "Doddie enjoyed a full life full of fun and love. And it was this approach to life which shone through in his determination to make a difference and help others when he was diagnosed with motor neurone disease.
"He inspired us every day with his positivity and energy and was fully committed to the work of the foundation he launched with his close friends in November 2017.
"My Name'5 Doddie Foundation continues to shine a light on MND and the need to seek meaningful treatments and, one day, a cure for this devastating disease."
Tributes flood in for Scotland legend Weir
'A fearsome warrior on and off the pitch'
Sky Sports News' Jamie Weir
"Doddie was a gentle giant, a big physically imposing second row. Sixty-one times he played for his country and he straddled the era between the game turning amateur into professional. He's also the only Scot to have ever scored two tries against New Zealand, in a World Cup quarter-final back in 1995.
"He was a larger than life character who was an inspirational leader for every Scotland player to have played alongside, and a hugely popular man in the wider game, too, a fearsome warrior on the pitch with that same strength and character off the pitch.
"Just a few weeks later after announcing he had been diagnosed with MND, he announced he was setting up a foundation, My Name'5 Doddie. They have raised millions upon millions for research into this horrible disease and hopefully one day a cure.
"He has been very visible and present in the last five years and just 13 days ago brought the match ball outside Kathy and his boys for Scotland's game against the All Blacks at Murrayfield.
"A hugely popular man, a tremendous rugby player, and what he's done over this last six years to try and fight this horrendous illness is testament to the mark he leaves on all the people whose lives he touched. He will be hugely missed."
Rory Lawson, former Scotland scrum-half, on Sky Sports News
"Doddie Weir as a rugby player was immense but beyond that... the more recent challenges and the way he's faced those, the way he's been a trailblazer and tried to find a cure for motor neurone disease, has been absolutely incredible.
"He will leave the world in a better place with all the work he and his foundation has done.
"He was a player who inspired many, but who also found fun in everything. He was a joker on and off the field and lit up every room he went into. It's incredibly sad to hear of what is sadly, inevitable news because motor neurone disease is one that breaks you down.
"Doddie's fight over five years has been one that has inspired many, he has fought it with such courage and humour.
"The way that he has faced the cruellest of diseases is just inspiring to so many people, and I think he is a loss that will be felt all the way around the world, in the rugby community and well beyond."