Father Alec Reid, an influential figure in the Northern Ireland peace process, has died in hospital in Dublin.
Fr Reid, who was born in Co Tipperary in 1931, died in St Vincent's Hospital early this morning.
Originally from Nenagh, he joined the Redemptorist Order and went on to spend four decades based at Clonard Monastery in north Belfast.
He is best-remembered as the priest who gave the last rites to two British army corporals, David Howes and Derek Wood, who were killed after they drove into a republican funeral.
In his effort to end the Troubles, Fr Reid facilitated talks between Sinn Féin's Gerry Adams and SDLP leader John Hume.
He was trusted by senior figures in the IRA and also met several taoisigh.
When the IRA eventually decommissioned its weapons in September 2005, he and Methodist minister Rev Harold Good witnessed the arms being put beyond use.
In recent years, he made several trips to Spain and worked to broker an end to the violent dispute in The Basque region.
President Michael D Higgins said Fr Reid will be best remembered for the "courageous part he played in identifying and nurturing the early seeds of an inclusive peace process".
The President said while Fr Reid spent the last few years of his life in Dublin, he would have been "gratified by the positive transformation that is under way throughout Northern Ireland, and especially in the Belfast that he loved so well".
Taoiseach Enda Kenny said: "Fr Reid made major contributions at so many critical times during the peace process.
"Like so many people on this island, I will never forget the tragic picture in 1988, when Father Reid was photographed administering the last rites to a British army soldier killed in west Belfast, demonstrating his deep respect for human dignity and life."
Mr Kenny also described are Fr Reid as an "extraordinary man with an extraordinary conviction" about his ability to bring people together in horrific situations.
Speaking in Loughrea, Co Galway, Mr Kenny said he had spoken to Fr Reid at length about his experience in the Basque Country.
He had told Mr Kenny that irrespective of how difficult some situations were, it was important that people were brought together and that there were catalysts and people to do that. Mr Kenny said Fr Reid was one such person.
He said his place in history was secure and the role he played in the peace process was very significant.
Tánaiste Eamon Gilmore said Fr Reid "made an essential contribution to the peace process during its most challenging and crucial periods".
He added: "He conducted himself with integrity and compassion even in the most difficult of circumstances. His deep respect for human dignity was evident at all times.
"We are the poorer for his passing today but Ireland is very much the richer for his labours."
Stormont First Minister Peter Robinson and Deputy First Minister Martin McGuinness also hailed Fr Reid's contribution.
Mr Robinson said: "Alec opposed violence and understood that the key to making progress was through reaching out to others, regardless of their background."
Mr McGuinness said: "Fr Alec Reid was a man of great dignity and his service to society embodied decency and respect for everyone."
He added: "He made an immeasurable contribution to the peace process and he has left a legacy of peace and hope for a better future for all."
Mr Adams described Fr Reid as a "chaplain to the peace process".
He said: "This was one person making a difference when in the entire establishment had refused to open up dialogue.
"And the whole credo of his gospel life was the dignity of human beings and the need for dialogue."
Rev Good said Fr Reid had done what others had failed to do and helped people hear each other and to trust themselves.
He said he would remember Fr Reid for his patience, unique ability to create trusting friendships and for being prepared to go into the no-man's land of the Northern conflict.
"Through persistent endeavour, to taking time with people, to helping to understand that they could no longer go on saying no and could no longer closing doors that the time had come for people to actually listen to each other and to hear each other ".
The Redemptorists said Fr Reid will be especially remembered for his work on the peace process and extended their "deepest sympathy to his family, friends and those who got to know him as a Redemptorist in the various roles and ministries he held".
Mr Hume described Fr Reid as a "pillar of the peace process".
The former SDLP leader and Nobel laureate said that without Fr Reid's "courage, determination and utter selflessness, the road to peace in our region would have much longer and much more difficult to traverse".
Northern Ireland Secretary Theresa Villiers also paid tribute saying "we all owe a debt of gratitude to him for the role he played in the peace and reconciliation process in Northern Ireland."
SDLP leader Dr Alasdair McDonnell said: "I was very saddened to hear of the passing of Fr Alec Reid who dedicated his life to ensuring peace was realised on this Island.
"His death reminds us that we haven't quite reached completion in terms of the peace process and we must re-double our efforts to achieve a lasting settlement.
"The courage and bravery displayed by Father Reid during the troubles has been a shining example to people right across the world."
Fianna Fáil leader Micheál Martin said: "It was with great sadness that I learned of the death of Fr Alec Reid this morning.
"Fr Reid played a pivotal role in bringing about peace in Northern Ireland. I was always struck by his humility and compassion for people on all sides of the Troubles.
"He had a remarkable capacity to put everyone he met at ease and his diplomacy, patience and influence led to the initiation of peace talks in the eighties which eventually lead to the Good Friday Agreement of 1998."
Fr Reid's remains will repose at Marianella Chapel on Orwell Road in Dublin from 2pm to 8pm tomorrow and from 1pm to 8pm on Sunday.
There will be mass in Marianella Chapel on Monday at 11am following which Fr Reid's remains will be brought to Clonard Church in Belfast where he will lie in repose on Monday between 4pm and 9pm and on Tuesday from 9am to 9pm.
An ecumenical service will be held on Tuesday at 7.30pm.
Fr Reid will be buried following funeral mass at Clonard Church next Wednesday at 12pm.