The long-standing Labour MP Paul Flynn has died aged 84, the party has announced.
Mr Flynn, who represented Newport West for 32 years, was described as an 'independent thinker' who would be 'greatly missed'.
He held several shadow cabinet posts during his parliamentary career, including a brief stint as shadow secretary of state for Wales in 2016, but had not been active in the Commons in recent months.
His constituency party said in a statement posted to Twitter on Sunday night: "It's with great sadness that we let you know that our MP, Paul Flynn, has died today.
"Paul is a hero to many of us in the Newport Labour family and we mourn for his family's loss. We would ask that the privacy of Paul's family is respected at this difficult time."
First Minister of Wales and Welsh Labour leader Mark Drakeford described Mr Flynn as a 'giant of the Welsh Labour movement'.
Labour leader, Jeremy Corbyn, said he was saddened at the passing of his "good friend".
Mr Flynn was a strong advocate for the medicinal use of cannabis, and in 2017 called for a second referendum on Brexit.
Speaking in the Commons in October that year, Mr Flynn asked: "Isn't it right that three years after the referendum, when we're thinking of taking this step, we allow the public to have a second opinion on this in the knowledge that second thoughts are always superior to first thoughts?"
He announced in October that he intended to stand down as an MP due to health reasons, telling the Press Association he would "wait for a convenient time to go" and had "loved every minute" of his time in Westminster.
He said at the time: "It's been a great, wonderful, rich experience. I lasted 31 years."
Politicians across the country and paid their respects to Mr Flynn as the news came in.
Speaker of the House of Commons John Bercow told ITV News he was "gutted" to hear of the news. "He loved parliament... he could speak about joblessness in his constituency... inequities of the benefits system, the problems of the criminal justice system. And he could talk about international affairs. He had very strong views about Afghanistan and Iraq and he was motivated always by doing what he thought was right".
Former leader of the Welsh Conservatives, Andrew RT Davies, said it was the 'end of a political era'.
Ealing Central and Acton MP Rupa Huq shared a photograph on Twitter of herself with Mr Flynn, and said they had served on the Public Administration and Constitutional Affairs Select Committee together.