Fr Gerry Reynolds (above, left) died of a short illness on November 30th at the age of 80.
The priest had been part of the Clonard Monastery in west Belfast, and worked for peace between Irish Protestants and Catholics for more than thirty years. His funeral was held there at midday on Thursday.
He was part of the Redemptorist movement within Catholic orders, which put particular emphasis on communion with other branches of Christianity, the ending of violence and social justice.
It was through Fr Reynold's work that former SDLP leader and Protestant John Hume and Sinn Fein leader and Catholic Gerry Adams met for the first time, in Clonard Monastery.
The meeting and Fr Reynold's other work was instrumental in the ongoing peace process to bring Northern Ireland out of the worst parts of The Troubles.
Sinn Fein leader Gerry Adams told the BBC that Fr Reynolds was "a champion of the peace process".
"He was central to efforts to develop a peace process years before it eventually took root.
"I want to extend to his family, and to colleagues in the Redemptorist Order, and to his many friends my sincerest condolences.
In a statement, Redemptorists at Clonard said: "He will be greatly missed by his Redemptorist confreres and colleagues, his family, friends, and the many people whose lives he touched through his ecumenical, peace and reconciliation ministries."