Stephen Martin has stepped down as Chief Executive Officer of the Olympic Council of Ireland (OCI) to pursue "other career interests".
The Co Down man, who won Olympic gold with the GB hockey team in 1998, was appointed CEO in 2006.
However, Martin will be the OCI Chef de Mission for the 2018 Winter Olympic Games in Pyeongchang.
Martin paid tribute to Olympic Games athletes for their "tremendous contribution to Irish sport".
He added: "As a former Olympian I recognise the commitment, dedication and sacrifices required.
"It has been my privilege and honour to work with them and I wish them every success in their sporting careers."
The 58-year-old competed for GB in three consecutive Olympic Games and also won a bronze medal in 1984..
He earned 229 international caps, 135 for Ireland, 94 for Great Britain and captained both teams.
Martin joined the OCI in 2006 following a career as deputy CEO of the British Olympic Association (Team GB).
"Stephen's experience and relationships with national and international sporting bodies were of value to the OCI over the past decade," said OCI president Sarah Keane.