Jacques Delors, a former head of the European Commission and key figure in the creation of the European Union's single currency, has died aged 98.
Mr Delors' daughter, Martine Aubry, said that her father died in his sleep in his Paris home.
He was a Socialist and had a high-profile political career in France, where he served as finance minister under president Francois Mitterrand from 1981 to 1984.
But he declined to run for president in 1995, despite being overwhelmingly ahead in the polls, a decision he later put down to "a desire for independence that was too great".
Mr Delors headed up the European Commission from 1985 to 1995, a decade that saw major steps in the bloc's integration.
These included the creation of the common market, the Schengen accords for travel, the Erasmus programme for student exchanges and the creation of the bloc's single currency, the euro.
His drive for increased integration met with resistance in some member states, particularly the UK under prime minister Margaret Thatcher.
"Up Yours Delors" read a famous 1990 front-page headline in The Sun newspaper, which voiced its concerns about a single currency and increased powers for the European Parliament.
Mr Delors later founded think tanks with the aim of furthering European federalism, and in recent years warned of the dangers of populism in Europe, also calling for "audacity" in dealing with the Brexit fallout.
He also urged more solidarity among EU members during the Covid-19 pandemic.
Delors 'a great Frenchman, great European' - Macron
French President Emmanuel Macron has described Mr Delors as "a tireless creator of our Europe".
In a social media post, Mr Macron said that "his commitment, his ideal and his rectitude will always inspire us" and he was "a statesman with a French destiny".
President of the European Council Charles Michel said Mr Delors was a "great Frenchman and a great European" who had "entered history as one of the builders of our Europe".
President Michael D Higgins said that Jacques Delors "will be rightly remembered as one of the foremost advocates for the best of what might be a truly inclusive European Union".
In a statement, he said that Mr Delors represented a "vision of a Europe which should respect all traditions and cultures, and be built around peace, mutual respect and dignity".
"Importantly ... he "recognised that economic needs must be balanced with the needs of society and that the new market demanded equal, if not greater, forms of protection for the citizen and the development of a Social Europe," President Higgins added.
Former taoiseach John Bruton described Mr Delors as "one of the most outstanding Europeans of the last century".
Mr Bruton said that he devoted his life to building, in the European Union, a structure of peace in Europe.
"The peace that he sought was based on mutual dependence rather than mutual rivalry.
"He was committed to a Europe with a social dimension to accompany its economic efficiency. It was my privilege to get to know him well during my time as Minister for Finance," Mr Bruton added in a statement.
Former Fine Gael leader Alan Dukes said that Mr Delors was a person he greatly admired, having first met him when he himself served as minister for finance in 1982.
"At the one time he was a visionary in the sense that he achieved enormous progress for the European Union and at the same time he was a realist and a pragmatist. This made it possible for him to achieve as much as he did.
Mr Dukes said that Jacques Delors also brought a strong sense of social commitment to the European Commission.
"He was avowedly Christian. He'd had a long career in trade unions in France and yet he called himself a social democrat and that really showed the flavour of his political thinking."
Additional reporting Eleanor Burnhill
