Right-to-die campaigner Marie Fleming will be remembered as a "brave and courageous" woman who left a lasting legacy by kick-starting a national debate, the Tanaiste has said.
The multiple sclerosis (MS) sufferer died at her home early this morning with her dedicated partner Tom Curran by her side.
She had lost a landmark Supreme Court case in Dublin in April, when lawyers argued he should be allowed help to end her life without fear of prosecution as she was physically unable to do it herself.
Mr Curran revealed the former academic passed away peacefully, but unexpectedly, at their home in Arklow, Co Wicklow.
"She was at home. That was her wish," said her partner of almost 20 years.
Her funeral will be held on Sunday.
Ms Fleming, who was due to turn 59 at the end of the month, went to Ireland's highest court in a bid to be allowed to end her life with assistance.
Diagnosed with MS in 1986, she had been wheelchair bound for several years, could only move her head, and was living in constant pain.
In her appeal to the court she revealed she cannot swallow, and feared a choking session would eventually kill her.
It has emerged she had suffered from several chest infections over the last few months and her health deteriorated in recent weeks.
Tanaiste Eamon Gilmore said his thoughts were with Mr Curran and with her children Corrinna and Simon.
"Marie's campaign on issues around the right to die was both brave and courageous," said the Labour Party leader.
"And while pursuing her campaign - at both political and legal levels - was always going to be a challenge, her deeply-held conviction meant it was one she was never going to back away from.
"Marie successfully highlighted the complex issues that affect people who find themselves in a situation like hers, and the fact that her case has kick-started a national debate on these matters will be her lasting legacy."
Mr Curran, an advocate for The Carers Association and a founding member of Right to Die Ireland, faced 14 years in prison if he had helped his partner to die.
He has campaigned tirelessly with and for Ms Fleming, raising her plight with Taoiseach Enda Kenny only last month.
The pair held talks just days after health chiefs forced the couple to prove Ms Fleming's sickness to have a medical card renewed.
Mr Kenny had told her partner he wanted to meet Ms Fleming, a former business studies lecturer, in her home.
Independent TD John Halligan, who led the couple's battle in the Irish Parliament, said Ms Fleming died at 5.30am.
"They are both very brave and loving people who cared for and loved each other deeply," he said.
"She was a very intelligent and articulate person.
"Her health had been getting progressively worse in the last few weeks.
"Tom had hopes she would make it through Christmas, but it wasn't to be.
"He knew this was inevitable, but it was still a shock. He is devastated."
He added that Mr Curran plans to continue his fight to change the law on assisted suicide in the new year.
"We are hoping to have a meeting with barristers, TDs and senators and take it from there," he added.
Sinn Fein's Caoimhghin O Caolain said Ms Fleming's ordeal touched the hearts of people across Ireland and beyond.
"Her courage and that of her partner won widespread admiration," he said.
"We owe it to her memory to approach with compassion and realism the debate on the issue of assisted suicide, conscious always of those who suffer such painful ordeals as that endured by Marie."
Billy Kelleher, Fianna Fail health spokesman, said he was saddened to learn of Ms Fleming's death.
"I want to extend my deepest sympathies to Marie Fleming's partner Tom Curran, her family and friends," he said.
"Marie Fleming battled her illness with fortitude and great dignity. Her campaign brought important issues into the public domain and she, along with her partner Tom, displayed huge courage throughout."