Sir Oliver Napier, the first leader of the Alliance Party, has died at the age of 75.
Tributes have been paid to Mr Napier, who was remembered as a statesman and visionary.
The Alliance was founded in 1970 to appeal to both Catholics and Protestants and heal divisions in communities. It is now the fifth largest party in Northern Ireland.
Mr Napier was its first leader from 1973 to 1984 and was also an Alliance minister in the 1974 Stormont powersharing executive.
Alliance leader David Ford said it was an extremely sad day for Northern Ireland.
“Oliver was a statesman and a visionary,” said Mr Forde. “His vision was of a united Northern Ireland and he put his heart and soul into bringing that about.
“He was ahead of his time but the vision he had is demonstrated in all the excellent work being done to improve community relations in Northern Ireland.”
Fianna Fáil leader Micheál Martin said Mr Napier “made a thoughtful and honourable contribution to the development of progressive politics” in the North.
Mr Martin said he was “always a strong and steadfast voice for peace and sanity” who never wavered from his conviction that both communities could come together and live in peace and harmony.
“He espoused an inclusive and tolerant approach to the problems of Northern Ireland. He trenchantly opposed sectarianism in all its guises,” Mr Martin said. “He will be sadly missed but his contribution to better days will long be remembered.”
Mr Napier is survived by his wife Briege, nine children and 23 grandchildren.
Born in Belfast, he was educated in St Malachy's College and took law at Queen's University before becoming a solicitor at his father's practice, Napier and Sons Solicitors.
He was knighted in the Queen's Birthday Honours List in 1985.