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Mrs Williams, 62, whose 15-year-old son Kevin died at Hillsborough, was one of the loudest voices throughout the campaigners' efforts for justice.
It was her fight to get her son's inquest verdict of accidental death overturned that is credited with leading to fresh hearings for all 96 Liverpool supporters who died.
She defied doctors' expectations to attend her last public appearance at the Hillsborough memorial service at Anfield on Monday, which was to be her last appearance in public.
Mrs Williams was diagnosed with terminal cancer in October, but despite her ill-health she carried on her campaign and attended a hearing at London's Royal Courts of Justice in December when the original inquest verdicts were quashed.
Speaking after the historic hearing, which she attended in a wheelchair, she thanked Attorney General Dominic Grieve for being "a man of his word'' in pushing for the new inquests.
She said: "I am glad we never gave up. It has been hard, but we wouldn't have been here today. "I'd like a corporate manslaughter verdict in the inquest, it's the least for what they have done.
"God willing, I will be here, it has been a long wait to see justice. "I am so glad I could be here today to hear it for myself.''
Referring to the cover-up that shifted blame away from the authorities and on to the victims, she said: "I can't forgive them the extremes they went to. Why didn't they just give us the truth?''
She missed out on seeing the start of the new inquest process by a week as a pre-inquest hearing will be held in London next Thursday to decide the timing and location for the new inquests.
Social media site Twitter was inundated with messages of support and condolence for her.
Liverpool FC posted a statement on Twitter saying: "Liverpool Football Club was this morning saddened to hear of the death of prominent Hillsborough campaigner Anne Williams. RIP Anne.''
Everton FC said: "The thoughts of everyone at Everton are with the family of Anne Williams, who sadly passed away this morning. RIP Anne #jft96.''
Mayor of Liverpool Joe Anderson said: "Terribly sad to hear about Anne Williams, an amazing and inspirational person. Her courage in the fight for justice is a lesson to us all.''
Maria Eagle, MP for Liverpool Garston and Halewood, tweeted: "So very sorry to hear about Anne Williams. She was an incredible inspirational woman. #RIP.''
Other friends and well-wishers took to Twitter to pay tribute to the campaigner who seemed to embody the spirit of the families who fought for justice for almost 25 years.
Paul Mac wrote: "Deepest sympathy to Anne's family a truly truly lovely woman and your with Kevin now Anne. We will never forget you x.''
Pp Corke said: "A truly inspiration Anne Williams. Every decent person on this planet has love and respect for long hard fight you fought Anne. Your with your Kevin now. Rest Anne. You av earned it. Lovely lady.''
Steve Monahan added: "R.I.P Anne Williams. What a true fighter and a wonderful woman. What she has had to endure for the last 24 years is a disgrace and it should never have been this long. But in the face of adversity she remained dignified and never gave up hope. If I'm half the parent she was when I have children I'll be doing well.YNWAx''
A tribute on the Liverpool FC website said Mrs Williams had been cared for during her illness at the home of her brother Danny and his wife Sandra in Birkdale, Liverpool.
The tribute continues: "It was an act so typical of a mum who simply refused to accept defeat.
"Like thousands of fellow Reds fans, Kevin said goodbye as he left to travel to Sheffield for the FA Cup semi-final against Nottingham Forest 24 years ago. Like 95 others, the teenager did not come home.''
Mrs Williams was an early chairman of the Hillsborough Justice Campaign and later independently established Hope For Hillsborough (For Justice) in an effort to secure a fresh inquest into her son's death.
On three separate occasions, an appeal was made to the incumbent attorney general for a new inquest, only to be rebuffed three times.
The European Court of Human Rights also rejected the case in 2009. The breakthrough was only achieved following the Hillsborough Independent Panel report last year.
She leaves behind two children, son Michael, 41, and daughter Sara ,33, and three grandchildren.
In a statement Steve Rotheram, MP for Liverpool Walton, said:
"Whilst Anne's death following her recent illness may have been expected it is no less painful to the family and friends that she leaves behind and I send my condolences to all those who knew and mourn her passing.
"Anne Williams' passing is a painful reminder of the families' long and arduous fight for justice. My sincere hope is that after a battle that demanded too much of her time and energy, Anne is now at peace with the son that was taken from her in April 1989.
"Hillsborough continues to be an enormous cross to bear for any of the families or survivors connected to that fateful day. The truth is, many of us will never know the physical, emotional and psychological toll of being involved with one of the greatest injustices in living memory.
"For many observers in Britain, Anne's story is the most well known as we have long been aware that her son Kevin was alive well past the 3.15pm cut off and that with a proper emergency plan deployed, he could have been saved.
"For almost a quarter of a century, the fight for truth and justice became the work of Anne's life. She was routinely let down by an establishment hell bent on protecting themselves rather than protecting the families.
"Kevin's last word before he died on the pitch at Hillsborough was 'Mum'. Anne's relentless pursuit of justice for her son personified the unyielding bond of a mother's love for her child. She was an inspiration to thousands of women across Merseyside and Britain.
"Despite her cruelly timed death today, Anne's story, like that of so many other families, continues to give me the resolve to fight for the 96 every single day that I am in parliament.
"In a week that saw the funeral of a woman described as the 'Iron Lady', Liverpool will mourn the loss of a real woman of steely determination.''