In 1968, as demonstrators and police clashed, Katz found herself at the center of history.
"In a steady, steady procession, cops with night sticks, tear gas just spewing all over the place towards the demonstrators," she recalled in 2018.
Speaking to ABC7's Craig Wall during the 50th anniversary of the DNC and those protests, Katz said she regretted the violence but not what the whole world saw.
"There's an integrity and honesty that, and a rightness about the issues, that lasts 'til today," she said. "If you stand for something and know what you're doing, then the arc of history usually proves you right."
It was one of many defining moments in a life devoted to activist and social justice. In 1983 Katz worked on Harold Washington's campaign, helping to elect the city's first Black mayor. And in 2002, she helped lead protests against the Iraq War in Chicago, where a young Barack Obama found his voice on an issue that would later propel him to the White House.
Katz would later work for Obama when he was a U.S. senator.
U.S. Rep. Jesus "Chuy" Garcia wrote, "Chicago has lost a progressive icon," saying she "helped build a more just politics for our city & country."
Chicago Mayor Brandon Johnson also commented on her death, saying, "From marching with MLK in Marquette Park to her work for Mayor Harold Washington, Marilyn was at the epicenter of Chicago politics for generations."