Sir Tasker Watkins, one of Britain's greatest war heroes, recipient of the Victoria Cross and an eminent retired judge, has died at the age of 88.
He was Welsh Rugby Union president for 11 years, and the national team wore black armbands in tribute for their opening World Cup game in Nantes.
He was 25 when he won Wales's first World War II Victoria Cross in France.
First Minister Rhodri Morgan said he was "one of the outstanding Welshmen of the 20th Century".
Mr Morgan called him a "unique institution," adding: "I don't think we'll see many more like Tasker Watkins".
Sir Tasker died in the University Hospital of Wales, Cardiff, in the early hours of Sunday, a few weeks after a fall at his home in the Llandaff area of the city.
New WRU president Dennis Gethin described Sir Tasker as "arguably the greatest living Welshman".
Mr Gethin, who was WRU secretary when Sir Tasker was president, said: "He was small in stature, but in every sense a colossus and Wales is a poorer place without him".
He said Sir Tasker was "without a doubt the greatest president the union ever had and the rugby world certainly mourn his passing."
"He was a man of integrity, loyalty and never forgot that he was from Nelson and to have known him and to have been a friend of his was one of the privileges of my life."
Sir Tasker with Princess Diana and Prince William at a rugby game
Asked why he believed Sir Tasker was the union's greatest president, Mr Gethin said: "Wales was having a rollercoaster of a time - as it always does in Welsh rugby - in the 11 years he was president, but he was the constant shining light.
"People throughout the world, even when Wales were doing badly, always respected Welsh rugby because of Sir Tasker Watkins."
WRU chief executive Roger Lewis said: "This is a sad day for Welsh rugby because Sir Tasker was a great follower of the game and a great Welshman.
"He was very supportive when I started with the union and I have grown to admire him and welcome his advice. He was widely known and respected at all levels of the game but he was especially passionate about his own club Glamorgan Wanderers, where he was president.
Wales captain Gareth Thomas said: "Sir Tasker was a man who had great respect from all the players, not just for his achievements as a person and as a war hero but for the way he respected Welsh rugby and everything that the players stood for.
"We all waited with anticipation for his after-match talks and I'm sure there will never be another person quite like him. "
Sir Tasker's distinguished career saw him excel in the military, in the law and in public life.
At just 25 and while serving as a lieutenant, he became the first Welshman in World War II to be awarded the Victoria Cross, Britain's highest honour for gallantry, for an assault on a German machine-gun post in northern France.
After the war ended he took up law as a career and rose through the legal system to become deputy lord chief justice.
He acted as deputy to the attorney-general in the tribunal into the 1966 Aberfan disaster when a coal tip slid onto the south Wales valleys village, killing 144 people, 116 of them children
He held senior posts in many walks of life and from 1993 to 2004, was president of the WRU, becoming its second longest-serving president.
After he stood down a new post of WRU honorary life vice-patron was created for Sir Tasker.
He was born in Nelson on 18 November, 1918, a week after the end of World War I.