Former Welsh first minister Rhodri Morgan has died aged 77.
The Labour politician was a "towering figure", former Welsh secretary Lord Hain said, describing him as "both the father of devolution and the father of the nation".
Labour leader Jeremy Corbyn hailed him as a "giant" of the Labour movement, while current Welsh Secretary, Conservative Alun Cairns, said Mr Morgan was a "significant politician" and a "great servant to Wales".
Described as "the Father of Wales", Mr Morgan spent more than 30 years in politics and led the country as first minister for almost 10 years from 2000.
He famously did not see eye-to-eye with former prime minister Tony Blair, who overlooked him to lead the Welsh Assembly in 1999, and moved to distance himself with New Labour.
Paying tribute to his predecessor, current First Minister Carwyn Jones said: "Wales hasn't just lost a great politician, we've lost a real father figure.
"In very many ways Rhodri wasn't like other politicians, and that is why people warmed to him, trusted him and felt like they knew him so well.
"He was funny, clever, engaging on almost any topic and absolutely passionate about all things Welsh.
"I owe him a great deal, just as we all do in Wales.
"He did so much to fight for, and then establish devolution in the hearts and minds of the public in our country.
"His bright confidence was infectious, and we can see much of Rhodri's can-do attitude in our modern Wales.
"That first decade of self-governance, and making distinct choices for Wales, will forever be associated with his leadership.
"He will be hugely missed, and my thoughts are with Julie and all the family at this sad time."
His wife, Julie Morgan, is Assembly Member for Cardiff North.
Mr Morgan made a name for himself on the Welsh political scene in 1987 after being elected as the MP for Cardiff West, working as shadow environment spokesman and chairing the House of Commons public administration select committee before assuming office in the Assembly in 1999.
Despite being initially overlooked for the post of first minister, he later took on the role in 2000 following the resignation of Alun Michael, now police and crime commissioner for South Wales.
After standing down as an MP in 2001, he retained his Assembly seat following the 2003 and 2007 elections - and managed to stay in the Senedd's top job in the case of the latter despite Labour not winning an overall majority and entering a coalition with Plaid Cymru.
In September 2009, on his 70th birthday, Mr Morgan announced he would be relinquishing his post as first minister - with Bridgend AM Mr Jones later succeeding him.
And around 12 months later, Mr Morgan announced he would be retiring from politics altogether.
Speaking ahead of stepping down, he said: "I am not a person who looks back.
"I made my decision. I stepped down in two stages and I think that's healthy in order not to get withdrawal symptoms."
Paying tribute, Lord Hain said: "He did more than anyone to bed down and ensure the new Welsh Assembly gained widespread legitimacy.
"Equally at home both bantering on rugby in a pub or talking economic theory, he was a unique populist intellectual.
"He was Welsh through and through and a repository of fascinating facts on everything under the sun.
"A towering figure in every sense whom we will all miss."
Mr Corbyn called Mr Morgan a "great man" and a "giant of the Welsh labour movement".
He said: "He stood up for Wales, its people's future and its public services."
Plaid Cymru leader Leanne Wood added her condolences, tweeting: "We have just heard the news that former First Minister of Wales Rhodri Morgan has passed away. Sincere condolences to Julie and the family."
And Andrew RT Davies, leader of the Welsh Conservatives, said Mr Morgan's death was "terrible news", calling him "a giant of devolved politics in Wales".
Former prime minister Tony Blair also paid tribute, calling him an "outstanding servant of Wales, the United Kingdom and the Labour Party".
After becoming first minister Mr Morgan vowed to put "clear red water" between the party in Wales and New Labour and when the former prime minister left office in 2007, he described Mr Blair as "a person who shafted me".
Mr Blair said: "He was great company, a fund of marvellous stories and a shrewd and immensely capable politician. We spent many times together in opposition and in Government.
"He took over the Welsh Assembly leadership at a difficult moment and led it with enormous skill and dedication.
"He will be sorely missed and I send my deepest condolences to Julie and the family."
Following his retirement from politics in April 2011 Mr Morgan said he planned to make the most of his retirement by catching up on his gardening and wood carving, as well as finally getting round to learning the piano.
But just six months later he was appointed chancellor of Swansea University.
The university said in a statement: "We are very saddened to hear of his death. Rhodri was a wonderful servant to the university as chancellor, as he was a wonderful servant to the whole of Wales.
"Our thoughts are with his family and his close friends."