Former prime minister Tony Blair has praised Ian Paisley's "decisive" contribution to the North's peace process.
This follows the DUP leader's announcement earlier that he would step down as First Minister in May.
Mr Blair said: "Ian Paisley's contribution to peace, after all the years of division and difference was decisive and determinative.
"In short, in the final analysis, he made it happen. The man famous for saying 'no' will go down in history for saying 'yes'.
"He did so personally convinced it was right and in reaching that conviction, consigning to the past the feelings he once so trenchantly articulated."
Prime Minister Gordon Brown said: "Ian Paisley has made a huge contribution to political life in Northern Ireland and the United Kingdom.
"The whole country values and admires the manner in which he has led as First Minister.
"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.
"We will continue to work with the parties to deliver the shared future for Northern Ireland to which he contributed so much."
Northern Ireland Secretary Shaun Woodward said Mr Paisley had provided "outstanding leadership" as First Minister and brought his party to the historic position of power-sharing in Northern Ireland.
He 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.
The "absolutely historic role" played by the Rev Ian Paisley in restoring devolved government was also praised by former Northern Ireland Secretary Peter Hain tonight.
Mr Hain worked very closely with the politician.
He said: "He played an absolutely historic role in ending the deadlock and establishing permanent devolved government and deserves enormous credit for the courage and vision he showed".
"I am sure that the decision he has taken will be the best one for his family as a very close family man. I wish him all the best for the future."
He went on: "I worked very closely with him leading up to this; we got on extremely well."
British Conservative Party leader David Cameron said: "Ian Paisley has been a formidable figure in British politics for many decades. "His term as First Minister of Northern Ireland has helped to forge a peace which many thought was impossible to achieve.
PA