A stalwart of Irish Rugby, Fergus Slattery earned 61 caps for Ireland between 1970 and 1984, and captained his country, on 18 occasions, with great distinction.
Renowned for his intelligence, work-rate, and leadership from the back row, he was at the heart of some of Ireland's most memorable performances of the era.
The Dubliner played a major role when the national team won the Triple Crown in 1982, for the first time in 33 years.
He was captain of the most successful Irish touring side ever in 1979, when they won seven of their eight matches in Australia, including the two Tests in Brisbane and Sydney.
On the international stage, Slattery's standing in the game was reflected in his selection for the British & Irish Lions, with whom he toured New Zealand (1971) and South Africa (1974), playing a central role in two of the most celebrated tours in Lions history.
When he made his last appearance for Ireland in 1984, he was the world's most-capped flanker. He was inducted into the International Rugby Hall of Fame in 2007, and World Rugby's Hall of Fame in 2015.
At provincial level, he was a key figure for Leinster and also proudly represented both Blackrock College and UCD, leaving a lasting legacy through his contribution to the game both on and off the field.
Commenting on today's announcement of his death, IRFU President John O'Driscoll said: "Fergus Slattery was a giant of Irish Rugby, and a player who defined excellence in his era.
"His leadership, skill, and unwavering commitment to the jersey set standards that continue to inspire generations of players.
"Off the field, he carried himself with humility and integrity, embodying the very best values of our game.
"On behalf of the IRFU, I extend our deepest sympathies to Fergus's beloved wife Margo, his daughter Nikki, son Cameron, and all his family, friends, and former team-mates at Blackrock College RFC, Leinster, Ireland, British & Irish Lions, and the Barbarians. He was a true friend whom I will miss greatly."
Fergus Slattery will be remembered not only as a world-class player, but as a true ambassador for Irish Rugby whose influence spanned generations.
The thoughts of everyone in the IRFU are with Fergus's family, friends, and former team-mates at this sad time.