Sinn Féin's Martin McGuinness has died in hospital.
The former Deputy First Minister in the North had stepped back from politics earlier this year after he was diagnosed with a rare heart disease in December.
It is reported that the 66-year-old died in hospital in Derry in the early hours of the morning.
Mr McGuinness stood down in January in protest at the DUP's handling of the 'cash for ash' energy scandal, triggering a snap election.
Ten days later, showing signs of physical frailty, he announced his retirement from frontline politics.
Speaking this morning, Sinn Féin President Gerry Adams TD 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.
“On behalf of republicans everywhere we extend our condolences to Bernie, Fiachra, Emmet, Fionnuala and Grainne, grandchildren and the extended McGuinness family.
“I measc laochra na nGael go raibh a anam dílis.”
Mr McGuinness was a former member of the IRA's army council and worked as Sinn Féin's chief negotiator during the peace process.
“Last year, Gerry Adams and I confirmed that we had a plan in place for transition to a new leadership,” Mr McGuinness said in January. “For my part, it was my intention to step aside in May this year which would have marked 10 years since I entered government with Ian Paisley as joint leader of the northern Executive.
"Unfortunately, my health and the current crisis have overtaken this time-frame and I am stepping down from my role to make way for a new leader of Sinn Féin in the North.”
He said his “obvious health issues” have forced him to be open and honest with his friends and colleagues in Sinn Féin, with the electorate of Foyle.
“Unfortunately, I am not physically able to continue in my current role.”
In 2007, the Democratic Unionist Party (DUP) agreed to share power with Sinn Féin and Ian Paisley and McGuinness became First Minister and Deputy First Minister.
In their first formal meeting as First and Deputy First Ministers, Paisley suggested sending a letter to the British Secretary of State asking him to immediately vacate Stormont Castle.
McGuinness once revealed that this was one of the "most amusing episodes" for him.
"We did so in our first joint letter as First and Deputy First Minister. The British Secretary of State and his staff were taken aback but did so.
"When we moved into our offices the following week, we discovered that they had taken everything with them, including the light bulbs."
What followed became a very public friendship. Images of the pair laughing and joking together earned them the nickname "The Chuckle Brothers".
"Our relationship confounded many. Of course, our political differences continued; his allegiance was to Britain and mine to Ireland. But we were able to work effectively together in the interests of all our people," McGuinness said after Paisley's death.
However, many in the DUP were unhappy with the friendship and, according to Paisley, he was forced to step down in June 2008.
A Twitter account in the name of Mr Paisley's son Kyle said: " Very sorry to hear about the passing of Martin McGuinness. Look back with pleasure on the remarkable year he and my father spent in office together and the great good they did together.
"Will never forget his ongoing care for my father in his ill health."
1/2 Very sorry to hear about the passing of Martin McGuinness.Look back with pleasure on the remarkable year he and my father...— Kyle Paisley (@JCKP1966) March 21, 2017
2/2 spent in office together and the great good they did together. Will never forget his ongoing care for my father in his ill health.— Kyle Paisley (@JCKP1966) March 21, 2017
In a wide-ranging interview on BBC Northern Ireland in January 2014, the former First Minister claimed he was edged out by senior figures in the DUP, after a canvass of the party found many MLAs were unhappy with his performance in the role, not least with his "chuckling" appearances alongside McGuinness.
After his death in September 2014, Paisley's widow Eileen revealed that McGuinness had been very supportive to the family during her husband's long illness and said their friendship had meant a great deal to her husband.
Speaking at an event in Belfast in October 2015, Mrs Paisley said: "During Ian's illness, he [Martin] contacted me.
"He would have texted me just to ask how Ian was, and say he was thinking about him. It was very precious to us as a family. It gave Ian a lot of happiness as well to know that he had left that impression with [him].
"His friendship with Martin McGuinness had meant something very special to him."
After Paisley's death, McGuinness himself spoke about their friendship.
"Despite our differences, I found him to be a charismatic and powerful personality. He always treated me and those who worked with me with respect and courtesy.
"The peace process and I have lost a friend," he said.
In 2012, after his historic handshake with the Queen, McGuinness said he “genuinely regretted” every life lost during the Troubles.
In a speech at Westminster he said: “Every single violent act was evidence of a failure of politics and a failure of British policy in Ireland.
“I genuinely regret every single life that was lost during that conflict and today I want every family who lost a loved one to know that your pain is not being ignored and I am willing to work with others to finding a way to deal with our past so that we can complete our journey to true reconciliation.”