Windsor is survived by her wife, Judith Kasen-Windsor, whom she married in October 2016.
"I lost my beloved spouse Edie, and the world lost a tiny but tough as nails fighter for freedom, justice and equality", Kasen-Windsor said in a statement.
"Edie was the light of my life", she said. She will always be the light for the LGBTQ community who she loved so much and who loved her right back. DOMA, which banned all federal recognition of same sex marriage, barred her from receiving those benefits.
In 1977, when Spyer was diagnosed with multiple sclerosis, Windsor cared for her around the clock; they married in 2007 in a Toronto ceremony officiated by Canada's first openly gay judge.
She had sued the USA government after being ordered to pay $363,053 (£224,940) in federal estate tax after her previous wife died. But public opinion and the legal landscape had undergone a sharp reversal, and Windsor prevailed in two lower courts before the US Supreme Court struck down the law. She was the grand marshal of the New York City Pride Parade that year and, per the Times, a runner-up alongside Pope Francis for Time magazine's Person of the Year.
Gay rights activist Edith Windsor, whose same-sex marriage fight led to a landmark United States ruling, has died aged 88.
Her lawyer confirmed her death to the Associated Press. While everyone else went out dancing, she waited up all night for Spyer to arrive-she finally showed up the next afternoon. With Edie's passing, I lost not only a treasured client, but a member of my family.
But all Americans, gay and straight, owe Edie Windsor a debt of gratitude. Windsor, an enthusiastic supporter of Clinton in her bid for the White House, said she was "so honored" the candidate chose her as a role model. Anthony Romero, executive director of the American Civil Liberties Union, called Windsor "one of this country's great civil rights pioneers". It is considered one of the most important LGBT rights cases in US history.
What began as a fight for a simple tax refund quickly became a testament to how far the nation had come in terms of support for same-sex marriage. In lieu of flowers, Windsor had requested, prior to her death, that any donations in her memory be made to The LGBT Center, Callen-Lorde, Hetrick-Martin Institute, and SAGE. "She touched countless lives, and we at GLAAD are deeply saddened by her passing, but her kindness, compassion, and legacy will endure".
The federal statute is invalid, for no legitimate objective overcomes the goal and effect to disparage and to injure those whom the State, by its marriage laws, sought to protect in personhood and dignity. "We immediately just fit - our bodies fit", she says in the film.