Church of Ireland Primate of All Ireland Alan Harper is to retire, he has announced.
Archbishop Harper, 68, had been a bishop for 10 years, having served as Bishop of Connor from 2002 to 2007. He is standing down at the end of September.
He was elected as Archbishop of Armagh in January 2007 and enthroned in St Patrick's Cathedral, Armagh, two months later.
A former chairman of the Historic Monuments Council for Northern Ireland (member 1980-1988, chairman 1988-1995), he was awarded an OBE for services to conservation in Northern Ireland in 1996. The Archbishop is married to Helen and has four children and 10 grandchildren.
A church spokesman said he would continue to carry out all the duties and responsibilities of the Archbishop of Armagh and Primate of All Ireland as normal until the end of September. The Church of Ireland House of Bishops will consider choosing his successor in due course.
The Archbishop of Dublin, the Most Rev Dr Michael Jackson paid tribute to what he described as the Archbishop's strong commitment to fairness and steadfastness in office.
He added: "Across the Church of Ireland, Archbishop Harper has sought to enable a wide range of voices to be heard on a broad spectrum of topics. He has worked systematically with the leaders of the other main churches in Ireland and has shown personal commitment in ecumenical relations and in the outworking of the Church of Ireland Methodist Covenant. He has also worked tirelessly in the development of a fresh understanding of community in Northern Ireland in the years of peace."
Cardinal Sean Brady paid tribute to Archbishop Harper, saying he had made a significant contribution to society in Ireland - north and south of the border.
"No doubt part of Archbishop Harper's pastoral legacy will include his contribution to the very positive and strong relationships which exist today between the Christian churches on the island, and to the continued progress of the peace process in Northern Ireland," Cardinal Brady said.
He also praised the Archbishop's personal compassion and commitment to social justice, and his support for the unemployed and disadvantaged.