IAN PAISLEY "is a giant figure in the history of these islands whose contribution will sit with Carson and Craig in the annals of unionist politics", the Taoiseach said last night.
Bertie Ahern praised the First Minister and Democratic Unionist Party leader for helping to bring about devolved government in Northern Ireland.
"We hope and pray that what has been achieved through the leadership of Dr Paisley, and others, will continue," the Taoiseach said.
British prime minister Gordon Brown also praised Dr Paisley for his commitment and dedication to public service.
He said: "The whole country values and admires the manner in which he has led as First Minister. Progress on bringing a lasting peace to Northern Ireland would not have been possible without his immense courage and leadership."
Northern Secretary Shaun Woodward said "the established peace and continuing prosperity which everyone in Northern Ireland now enjoys undoubtedly owes a significant debt to the leadership of Dr Paisley".
Deputy First Minister Martin McGuinness praised what he called the courage and leadership of Dr Paisley.
"I will look back fondly on the relationship I had with Ian Paisley over the course of the last 10 months," he said.
Speaking from Dubai where he is on official business, he added: "He and I and others have been part of probably the most important political breakthrough seen in the history of the island of Ireland."
Fine Gael leader Enda Kenny said Dr Paisley deserves considerable credit for his role in establishing the Northern Ireland Executive and Assembly.
"For 40 years, he was the dominant figure in Northern Irish politics," he said.
His most likely replacements, Peter Robinson or Nigel Dodds, are practical politicians, he said.
Sinn Féin president Gerry Adams commended Dr Paisley for his "crucial role in forging the agreement that restored the political institutions".
However, Jim Allister, of the Traditional Unionist Voice, who quit the DUP over its decision to enter the Executive with republicans, said Dr Paisley's legacy was "spoiled" by his call to share power with Sinn Féin.
UUP deputy leader Danny Kennedy said: "The attacks on Ian Paisley jnr were used as proxy attacks on Ian Paisley snr and were aimed deliberately at weakening his overall political position."
SDLP leader Mark Durkan said that while Dr Paisley's resignation is very significant political news, "there is responsibility on all of us as politicians to make the most of the political processes here, no matter who comes or goes.
Alliance leader David Ford said: "History will judge whether Ian Paisley will be remembered for 40 years of saying 'no' or one year of saying 'probably'."
Labour leader Eamon Gilmore said: "I wish him well in his retirement . . . In recent years, he has expressed a very positive role and for that I think the country has to express a note of gratitude.
"History will have to weigh up the extent to which he contributed to the problem and the extent to which he contributed to the solution," he said.