Ex-IRA chief Martin McGuinness dined with Queen and negotiated end to violence
Martin McGuinness was a former IRA commander who shook the Queen's hand and dined at her table.
In 1972 it would have seemed absurd that she would one day greet a man who helped lead the Provisionals in a bloody campaign against British rule in Northern Ireland.
The Saville Inquiry into Bloody Sunday said he "probably" carried a sub-machine gun during the massacre of 14 unarmed civil rights protesters by soldiers in Londonderry.
He admitted to being second-in-command of the IRA that day.
A former butcher from the Bogside in Derry, a man of action during the street fighting of the 1970s, he ended up toasting the Queen at Windsor Castle after a long career of peace-making.
Mr McGuinness was Sinn Fein's chief negotiator of the 1998 Good Friday peace agreement which ended violence, secured IRA arms decommissioning in 2005 and shared government with former enemies in Belfast as deputy first minister.
During his time as DFM he forged such a good working relationship with former Democratic Unionist Party (DUP) leader and first minister Ian Paisley that they were dubbed "the Chuckle Brothers".
But it was his more strained relationships with Mr Paisley's successors, Peter Robinson and Arlene Foster, that led to difficulties in recent years at the top of the power-sharing executive.
Recently he has been plagued by ill-health, being forced to withdraw from a business trip to China with Ms Foster on medical advice.
When he announced his resignation in Belfast earlier this month he appeared gaunt and tired.
Under the power-sharing arrangements he took the first minister with him, ending a decade of testy coalition government with the DUP and forcing an election.
A republican who vowed to bring about a united Ireland, he had always acknowledged his IRA past.
In 1973 he was convicted by the Republic of Ireland's Special Criminal Court after being arrested near a car containing explosives and ammunition.
After his release, and another conviction in the Republic for IRA membership, he became increasingly prominent in Sinn Fein, eventually becoming its best known face after Gerry Adams.
He was in contact with British intelligence indirectly during the hunger strikes in the early 1980s, and again in the early 1990s .
Mr McGuinness became Sinn Fein's chief negotiator in the talks that led to the Good Friday Agreement.
He became MP for Mid Ulster in 1997.
After the Good Friday Agreement was concluded, he was returned as a member of the Assembly for the same constituency, and nominated by his party for a ministerial position in the power-sharing executive, where he became minister of education.
He scrapped the 11-plus exam, which he had failed as a schoolboy.
The Good Friday Agreement proved difficult to implement and was followed by the St Andrew's Agreement in 2006.
Sinn Fein ambitions such as a bill of rights for Northern Ireland and an Irish language act are still unfulfilled.
But the very act of the DUP and Sinn Fein, once staunch enemies, entering into coalition government with Mr Paisley and Mr McGuinness at its helm was epoch-making for Northern Ireland.
In December 2007, while visiting US president George W Bush at the White House with Mr Paisley, Mr McGuinness said: "Up until the 26th of March this year, Ian Paisley and I never had a conversation about anything - not even about the weather - and now we have worked very closely together over the last seven months and there's been no angry words between us.
"This shows we are set for a new course."
Mr McGuinness' dream of a united Ireland was unfulfilled during his tenure.
Doubts remain among some republicans about what they have gained through entering Stormont.
But his period in office helped consolidate the peace and repair some of the many fissures in a once-bitterly divided Northern Ireland.