“It is with great sadness that the family of Lord Trimble announces that he passed away peacefully earlier today following a short illness,” the UUP said in a statement.
No other details were provided about his death.
Trimble, who led the party for a decade from 1995, had served in the House of Lords, the upper house of Britain’s parliament, since 2006, serving as a Conservative peer.
“A political giant, a brave politician, a staunch trade unionist and friend,” current UUP leader Doug Beattie said on Twitter, adding in a statement that he was “a man of courage and vision. “.
The 1998 Good Friday Agreement largely ended 30 years of conflict in Northern Ireland that claimed 3,500 lives and is still hailed as a shining example of political skill.
Despite resistance within his Unionist community, which favors ties between Northern Ireland and mainland Britain, Trimble brought his cohort to the table of the long-running peace talks.
As part of the peace process, he became the first party leader in 30 years to meet the Irish premiere in Dublin and in 1997 he became the first Unionist leader since partition to negotiate with the Republican party Sinn Fein.
Following the 1998 deal, he served as First Minister of Northern Ireland, alongside SDLP Deputy Leader Seamus Mallon as Deputy First Minister.
Brandon Lewis, who resigned as UK government secretary for Northern Ireland earlier this month, called him “a brilliant statesman and a dedicated civil servant”.
“His legacy as the architect of the Good Friday Agreement will live on forever,” he tweeted.
“The British people owe him a huge debt of gratitude for all he has done for our Union.”