Taoiseach Bertie Ahern said the announcement by Ian Paisley that he will step down from the post of First Minister is a watershed in the history of Ireland.
'He is a giant figure in the history of these islands, whose contribution will sit with Carson and Craig in the annals of unionist politics.
'In recent years, I have grown to know Dr Paisley and have valued the practical and friendly working relationship that developed between us.'
Mr Ahern said in time history will come to a fuller judgement of the many aspects of his long career.
Fine Gael leader Enda Kenny said Mr Paisley was a controversial figure over a lengthy political career, who showed real conviction in establishing the power-sharing Assembly.
While Labour leader Eamon Gilmore said Mr Paisley has had a remarkable record of public representation at local, national and European level.
He added that the Ian Paisley who resigns as First Minister is very different to the Mr Paisley who first led opposition to the civil rights movement and to cross-border co-operation in the 1960s.
UK leaders add their tributes to Paisley
British Prime Minister Gordon Brown said tonight Ian Paisley had made a huge contribution to political life in Northern Ireland and the UK.
'His commitment and dedication to public service deserve our gratitude. Progress on bringing a lasting peace to Northern Ireland would not have been possible without his immense courage and leadership,' he said.
Former prime minister Tony Blair praised Mr Paisley's 'decisive' contribution. He said of the power-sharing executive, 'in the final analysis, he made it happen. The man famous for saying 'no' will go down in history for saying yes'.
Northern Secretary Shaun Woodward said Mr Paisley had provided outstanding leadership as First Minister. 'The established peace and continuing prosperity which everyone in Northern Ireland now enjoys undoubtedly owes a significant debt to the leadership of Dr Paisley,' he said.
Scotland's First Minister Alex Salmond said Dr Paisley's remarkable political career would be looked upon as culminating in the triumph of power-sharing and the resumption of devolved government in Northern Ireland.
Conservative Party leader David Cameron said Mr Paisley had been a formidable figure in British politics for many decades.
His willingness to work closely with former opponents to build a new future for Northern Ireland had captured the world's imagination, Mr Cameron said.
Liberal Democrat leader Nick Clegg described Dr Paisley as a central player in the process of huge and historic change in Northern Ireland.
Former Northern Ireland Secretary Peter Hain said Mr Paisley's historic role in ending the deadlock deserved enormous credit for the courage and vision he showed.
