By Mark Devenport
BBC Northern Ireland political editor
His bearded face is well known in many countries throughout the world.
For some he was a hate figure, an apologist for IRA violence.
For others he is Northern Ireland's Nelson Mandela, the man who was unlucky not to win a Nobel prize for shifting his movement from armed struggle to peaceful politics.
Gerry Adams has never shied away from taking big decisions
One thing Sinn Fein President Gerry Adams has never shied away from is taking big decisions.
In the 1980s he was a key player in the IRA hunger strikes. In the 1990s he brokered the IRA ceasefire and the acceptance of places in a Northern Ireland Assembly.
In the 21st century he was ready to abandon another long held republican shibboleth - opposition to the police in Northern Ireland.
Given the personal and political risks he has taken, Gerry Adams's leadership skills in navigating these sea changes in policy cannot be underestimated.
Historically, disagreements between republicans led to violent feuding, but during the peace process, major splits have largely been avoided.
Gerry Adams is always careful to use close supporters to test controversial ground in advance, ruthless in isolating and marginalising his opponents and far-sighted in never allowing the swirl of events to knock the strategic direction of his "project" off course.
Born in October 1948, in his youth he worked as a barman in a Belfast city centre bar where he was fascinated by the political gossip traded among its clientele of journalists and lawyers.
However, as the civil rights movement gathered pace in the late 1960s, the young Adams did not spend long pulling pints.
Soon he was out on the streets, involved in the protests of the time.
According to his own account, he was purely a political activist.
But his family was steeped in the traditions of the IRA. His father was jailed in the organisation's campaign during World War II.
Security sources insist young Gerry followed suit and was a leading member of the IRA in Belfast at the time of the Bloody Friday bombings in 1972.
During the prison hunger strikes of the 1980s, Gerry Adams recognised the lessons of Bobby Sands's election as MP for Fermanagh-South Tyrone.
After the hunger strikes, the IRA did not reduce its commitment to "armed struggle" but its political wing, Sinn Fein, increasingly looked to the propaganda potential of fighting elections.
Gerry Adams's own election victory in west Belfast in 1983 marked a major achievement for this dual "armalite and ballot box" strategy.
Soon afterwards, Gerry Adams brushed aside the old southern leadership of Sinn Fein, led by Ruairi O Bradaigh.
Gerry Adams uses close supporters to test controversial issues
Together with Martin McGuinness, he was now in an unrivalled position to guide republican strategy.
Sinn Fein's electoral successes unnerved the British and Irish governments.
They came up with the 1985 Anglo-Irish Agreement, partly in an attempt to shore up the constitutional nationalism of John Hume's SDLP.
However, within three years of the agreement, John Hume and Gerry Adams held private talks.
The Hume-Adams process eventually delivered the 1994 IRA ceasefire which ultimately provided the relatively peaceful backdrop against which the Good Friday Agreement was brokered.
In 1986, Mr Adams dropped Sinn Fein's policy of refusing to sit in the Irish parliament.
In 1998, 90% of the party backed their president in taking seats in the new Northern Ireland Assembly at Stormont - a remarkable piece of political management given Sinn Fein's "no return to Stormont" slogan in the 1997 general election campaign.
Mr Adams stayed out of the Stormont power-sharing executive, letting Martin McGuinness take a ministerial post.
When the power-sharing deal collapsed amidst recriminations over IRA activity and its failure to disarm, Gerry Adams became a key player in the government's attempts to broker a new agreement between him and his bete noire, Ian Paisley.
The negotiations foundered at the end of 2004, but in October 2006 both Mr Adams and Mr Paisley indicated their support for the St Andrews Agreement, drawn up after intensive talks in Scotland.
A key element of the deal was Sinn Fein support for the police, who the IRA had once deemed "legitimate targets".
Mr Adams had already signalled his intent by meeting Northern Ireland's Chief Constable Hugh Orde in December 2004.
A further meeting took place on camera at Stormont as the Sinn Fein president signalled that backing the forces of law and order was "the right thing to do".
For some former followers this was a step too far.
In the 1980s, Gerry Adams survived an assassination attempt by the loyalist paramilitary UDA, who sprayed his car with bullets while he drove through central Belfast.
This was just one of many loyalist plots to murder him.
But in January 2007, he visited loyalist east Belfast to attend the funeral of David Ervine, the former UVF prisoner who became a strong advocate of the peace process.
Such a visit would have once been inconceivable, but Adams' embrace of Mr Ervine's widow appeared highly symbolic of the Sinn Fein president's political trajectory.
In recent years, against the backdrop leading up to the Hillsborough Agreement in February 2010, Mr Adams has had a media spotlight on his family.
In December 2009, Mr Adams revealed that his late father subjected family members to emotional, physical and sexual abuse over many years.
In a separate case, his brother Liam Adams is wanted over claims he sexually abused his now grown-up daughter from the age of four.
His alleged victim, Aine Tyrell, waived her right to anonymity in 2009.
The Sinn Fein leader, who had known about the allegations for over 20 years, has come under pressure to explain why he did not do more to prevent his brother from working with children while the claims were investigated.