She continued the character on her own spin-off, "Rhoda," and in a TV movie back in 2000.
Now all these years later, she's writing about those years in a new memoir due out early next year.
"I will focus on Rhoda and Mary and people's relationships with Rhoda and my life, my early life, things they may not know about me. And so it's going to be a romp," said Harper. "And I have so many stores about them that haven't been heard."
Harper is also busy campaigning for her stepson, Michael Caccioti, the three-term mayor of South Pasadena, who is now running for the state assembly.
Harper is also on the campaign to help raise money for isolated, impoverished and forgotten holocaust survivors in Eastern Europe.
The Survivor Mitzvah Project is a grassroots effort dedicated to helping those who've never gotten reparations from Germany because they weren't in concentration camps.
"And the key thing, George, is that they're doing what no one else is doing. There's no other organization like this and they are bringing desperately needed help directly and continuously to these folks," said Harper.
To keep helping these folks, Harper, Ed Asner, Elliot Gould, Frances Fisher and others will perform in a fundraiser April 22 at the Museum of Tolerance in a show called "The Stars come out to help Survivors."
"It's going to be an evening of entertainment but very meaningful because we will read letters from the recipients of the beautiful commitment of this organization," said Harper. "If you ever saw 'Schindler's List' or 'Sophie's Choice' and you go, 'Oh god! What could I do? What a horrible thing.' This is the thing. Let's let these people who've suffered so horribly really go out in some kind of comfort and dignity."
Doors for the show open at 6:45 p.m. with curtain at 7:30 p.m. Tickets are $360 and can be purchased through the event website, or by calling (800) 905-6160.