Republican playwright and journalist Brian Campbell died suddenly near his home in Newry on Saturday.
It is believed the former republican prisoner suffered a massive heart attack.
The 46-year-old father-of-two became ill after he had been out running on Saturday. It is understood he died as he was being taken to hospital.
Softly-spoken and with a ready smile, Brian was well known and liked throughout the republican movement and beyond.
A former editor of An Phoblacht/Republican News, Brian won acclaim as a playwright and screenwriter before working with Conor Murphy to elect him as Sinn Fein MP for Newry and Armagh.
Arrested in 1986, he met hunger strike surviver Laurence McKeown, his collaborator in two plays - The Laughter of Our Children and A Cold House.
The pair also wrote H3, a film about the 1981 hunger strike.
While in prison the men edited the book Nor Meekly Serve My Time, in which former hunger strikers told their stories of the prison struggle of the late 1970s and early 1980s.
Conor Murphy said last night that there was “huge shock” at Brian’s death.
“The sudden death of Brian Campbell is a devastating blow to all of us who knew him well and to the entire republican family,” he said.
“Brian was a hugely talented individual who made an enormous contribution to the development of republican politics and writing, not just in Newry and Armagh, but across Ireland.
“He was active in so many fields - political, cultural, community and sporting and yet was first and foremost a devoted husband and father.
“His untimely death has caused huge shock and deep sadness among his friends and comrades and his loss will be keenly felt both within republican circles and beyond.
“Our deepest sympathy goes to Grainne, Niall and Mairead and the Campbell family at this tragic time.”
Sinn Fein president Gerry Adams said: “Brian Campbell was a man of enormous talent and commitment to the republican struggle. Republicans throughout Ireland were deeply shocked yesterday when we heard the news of Brian’s sudden death.”
Lawrence McKeown also aid tribute to him.
“Brian was educated in England and qualified as a mechanical engineer. The 1981 hungerstrike and the death of Martin Hurson impacted on him greatly and prompted his involvement in the struggle. He ended up in prison in the mid-1980s and was sentenced to 16 years. He came into the blocks and became really involved in creativity and politics.
“He was the first editor of the Captive Voice and produced it to such a standard that it was able to be read as a magazine of interest outside of the jail. It gave a flavour of the meaning of life to prisoners.
“He also compiled Nor Meekly Serve My Time.
“He was a republican socialist who could reach out to the community, people young and old and unionists. He had manners and a great civic spirit. IRA volunteers have often been demonised as terrorists. Brian showed throughout his life that he was a humane and progressive man. He was humble and a very likeable person - he was a doer as well as a thinker - calm, confident and unassuming,” Mr McKeown said.