Lilly Ledbetter, whose name graces an equal pay law in the US, has died aged 86.
CBS, the BBC's news partner in the US, quoted her children as saying she died peacefully on Saturday surrounded by family and loved ones.
"Our mother lived an extraordinary life," added a family statement.
Ms Ledbetter's activism led to the first bill signed into law by Barack Obama after he became US president in 2009.
The Lilly Ledbetter Fair Pay Restoration Act made it easier for workers to sue after discovering they were being discriminated through pay.
Mr Obama said that the law sent the message "that there are no second-class citizens in our workplaces".
Ms Ledbetter worked as a supervisor for Goodyear, the tyre manufacturer, in Alabama for nearly 20 years before discovering she was being paid less than men doing the same job.
The Supreme Court ruled in 2007 that she had no grounds to sue because her complaint had not been lodged within six months of the discrimination first taking place. Her law overturned that ruling.
The former president paid tribute on Twitter/X, saying Ms Ledbetter "never set out to be a trailblazer or a household name. She just wanted to be paid the same as a man for her hard work".
"Lilly did what so many Americans before her have done: setting her sights high for herself and even higher for her children and grandchildren," Mr Obama said.
Ms Ledbetter continued her advocacy after the law was signed.
She received the Future Is Female Lifetime Achievement Award from Advertising Week last week, according to the Alabama news site AL.com.
A new film about her life, called Lilly and starring Patricia Clarkson, has recently been shown at the Hamptons International Film Festival.