The death has occurred of the noted historian Professor Ronan Fanning.
President Michael D. Higgins led the tributes to "a much admired and respected historian whose extensive research and writings delivered a rich legacy to Irish scholarship".
He described him as "an accomplished author and frequent broadcaster" who "possessed a rare and wonderful talent for capturing and enrapturing his audience with an energetic and passionate literary style".
“He will be fondly missed by his colleagues in academic life and by all of us who had the privilege of knowing him," President Higgins said.
President Higgins and his wife Sabina expressed condolences to Professor Fanning’s family, colleagues and wide circle of friends.
National University of Ireland (NUI) Chancellor, Dr Maurice Manning said "his loss will be keenly felt".
Dr Manning said the country "had one of the most eminent historians of modern Ireland".
He described Professor Fanning, who was Professor of Modern History in UCD, as a 'brilliant teacher; he encouraged and inspired new generations of Irish historians'.
For years, Professor Fanning was a regular columnist with the Sunday Independent and last year contributed to the series of 1916 commemoration supplements, jointly produced by the Irish Independent and UCD.
Dr Manning said; "Through his journalism his views reached a wide audience."
He said Prof Fanning brought his considerable academic talents to bear on the study of many aspects of modern Irish history.
He was the author of the authoritative biography 'Éamon de Valera: A Will to Power', which followed in a list of very distinguished publications stretching back to his 'The Irish Department of Finance 1922-58'.
He was also joint editor of the Dictionary of Irish Biography (2009) and of Documents on Irish Foreign Policy.
Dr Manning said he made a substantial contribution to expanding the resources available for scholarship.
Meanwhile, UCD president Professor Andrew Deeks, said news of the death of the UCD Emeritus Professor was met with “"deep sadness within UCD. He was one of our leading historians. He contributed to the university in countless ways over many years".
Professor Deeks said Prof Fanning was "truly gracious with his guidance and advice".