With a reputation as an unforgiving negotiator with ice in his veins, Peter Robinson is viewed as a hardline leader of the DUP.
The former estate agent, who won his Westminster seat at the age of 30, has been central to the party since its inception more than four decades ago.
However, a series of personal and party scandals have taken their toll over the past five years, while intense political rows over issues including welfare reform and same-sex marriage have heaped further pressure on the 66-year-old father of three.
Firebrand oratory
Born in Belfast, and schooled at Annadale Grammar in the south of the city, he was inspired by the firebrand oratory of the Rev Ian Paisley and joined him in his battle to protect Ulster from the hands of republicans.
In 1985 he was at the forefront of the pan-unionist campaign against the Anglo Irish Agreement - an accord between the British and Irish governments which gave Dublin a role in affairs in Northern Ireland.
In his latter career he has been a trenchant opponent of all forms of paramilitarism, but in the dark days of the Troubles the lines were somewhat blurred. He was arrested in 1986 in the village of Clontibret, in the Republic, after taking part in a so-called “invasion” along with a large group of loyalists.
He later pleaded guilty to unlawful assembly.
Mr Robinson and his party colleagues opposed the 1998 Belfast Agreement, citing its release of paramilitary prisoners as abhorrent.
Although he took office as minister for regional development in the newly created power-sharing executive, he refused to take part in cabinet meetings.
The eventual collapse of that assembly benefited the DUP at the polls and they soon displaced the Ulster Unionists as the largest unionist party in Northern Ireland.
St Andrews Agreement
In 2006, they negotiated the St Andrews Agreement which paved the way for the latest assembly.
Peter and Iris Robinson became the equivalent of Northern Ireland's first couple when he realised his long-term ambition and became Stormont First Minister and DUP leader after the retirement of Ian Paisley in 2008.
However, Ms Robinson, a born-again Christian, sparked outrage and a police investigation when she described homosexuality as an abomination and claimed gay people could be “cured”.
In 2010 he temporarily stepped aside as First Minister when details of his wife’s affair with teenager Kirk McCambley were revealed.
His 35-year political career came close to ruin after it emerged Ms Robinson had asked two property developers to lend her £50,000 to fund a new business for her youthful lover.
A subsequent investigation by the Assembly’s Standards committee exonerated Mr Robinson but found that his wife, a former Strangford MLA, had breached the code of practice.
Ms Robinson has since resigned from politics.
Press Association