Former British prime minister Margaret Thatcher has died following a stroke, aged 87.
Her spokesman Lord Bell confirmed the news, saying: "It is with great sadness that Mark and Carol Thatcher announced that their mother, Baroness Thatcher, died peacefully following a stroke this morning."
Mrs Thatcher was the longest-serving British prime minister in the 20th century and the only woman to have ever held the post.
British PM David Cameron praised her as a "great leader" and a "great Briton".
Labour leader Ed Miliband said she had "moved the centre ground of British politics", and former British prime minister Tony Blair credited her with changing the world.
Global leaders added their voices to the tributes, with US President Barack Obama saying Mrs Thatcher had been a "true friend" to the US.
Mr Cameron cut short an official trip to Europe and announced that parliament was being recalled from its Easter recess on Wednesday to give MPs the chance to pay tribute.
Labour and the Tories have suspended campaigning ahead of next month's key local elections, and the Lib Dems are also not expecting to hold any events. Flags were flying at half-mast on public buildings.
President Michael D Higgins said Mrs Thatcher's role in signing the Anglo-Irish Agreement would be recalled "as a valuable early contribution to the search for peace and political stability".
Taoiseach Enda Kenny said he was saddened to hear of the former prime minister's death.
Describing her as a formidable leader, Mr Kenny said during her 11 years in office "she defined an era in British public life".
However, opinion in Northern Ireland was divided on her role in Anglo-Irish relations, with Sinn Féin leader Gerry Adams saying she did "great hurt to the Irish and British people".
He said: "Here in Ireland her espousal of old draconian militaristic policies prolonged the war and caused great suffering."
Former SDLP leader Seamus Mallon said her handling of the Hunger Strike in the 1980s ultimately suited the position of the Provisional IRA and still affects politics on the island of Ireland.
Northern Ireland First Minister and DUP leader Peter Robinson said: “Whilst we disagreed over the Anglo-Irish Agreement, Mrs Thatcher was committed to the Union and later described the Anglo-Irish Agreement as one of her greatest regrets."
A ceremonial funeral with military honours, a tribute usually reserved for senior members of the royal family, will be held for Mrs Thatcher at St Paul's Cathedral in London next week.