Martin McGuinness has died at the age of 66.
He had stepped down as Northern Ireland's Deputy First Minister in January and had been unwell for several months.
He was a former member of the IRA's army council and worked as Sinn Fein's chief negotiator during the peace process.
Paying tribute this morning, Sinn Fein President Gerry Adams described Martin as a passionate republican who worked tirelessly for peace and reconciliation and for the re-unification of his country.
The Sinn Féin President said “Throughout his life Martin showed great determination, dignity and humility and it was no different during his short illness.
“He was a passionate republican who worked tirelessly for peace and reconciliation and for the re-unification of his country. But above all he loved his family and the people of Derry and he was immensely proud of both".
While, President Michael D Higgins said "It was with great sadness that I have heard of the passing of Martin McGuinness, and on behalf of Sabina and myself, may I express our deepest sympathy to his wife Bernadette and to his family.
The world of politics and the people across this island will miss the leadership he gave, shown most clearly during the difficult times of the peace process, and his commitment to the values of genuine democracy that he demonstrated in the development of the institutions in Northern Ireland.
As President of Ireland, I wish to pay tribute to his immense contribution to the advancement of peace and reconciliation in Northern Ireland – a contribution which has rightly been recognised across all shades of opinion.
As a political colleague of many years, and having participated together in the Presidential election campaign of 2011 that brought us all over Ireland, Sabina and I have appreciated both Martin McGuinness’ warmth and his unfailing courtesy.
Our paths have crossed many times in recent years at official events, including most recently at the GPO for the 1916 commemorations, as well as in our celebrations of ‘the beautiful game’, at Glentoran and in France at the European Championships.
In addition to his services in public life, as an inclusive believer in community in all its forms he will also be remembered for his warm support for Derry GAA and Derry FC.
His death leaves a gap that will be difficult to fill. May he rest in peace.”
At the time, Martin cited the 'Cash For Ash' scandal as the reason he was stepping down for active politics. Despite tension betweeen the pair over the past months DUP leader Arlene Foster said "I want to express my sincere condolences, both personally and on behalf of our party, to the McGuinness family upon hearing the news of the passing of Former Deputy First Minister Martin McGuinness. Today's news will come as a shock to many people. First and foremost, Martin McGuinness was a much loved husband, father and grandfather. My thoughts and prayers are with his wife and the family circle at this very painful time of grief and loss."