As Edna Krabappel on The Simpsons, Marcia Wallace may be the only 4th-grade teacher to have the same student for 24 years. Before that, she was beloved as Carol Kester, the lovelorn, wisecracking secretary on The Bob Newhart Show.

Wallace, who was a breast cancer survivor for 28 years, has died at age 70, according to the showrunner of The Simpsons. “I was tremendously saddened to learn this morning of the passing of the brilliant and gracious Marcia Wallace,” producer Al Jean said in a statement to EW. “She was beloved by all at The Simpsons and we intend to retire her irreplaceable character.”

It has become a sad tradition of the extremely long-running show to simply cease using characters whose voice actors pass away. The first instance was when Phil Hartman died in 1998, and the show retired his sleazy attorney Lionel Hutz and desperate pretty-boy actor Troy McClure. Lunchlady Doris was retired as a speaking role for nearly a decade after actress Doris Grau’s death in 1995, but has made brief appearances since 2006 with Tress MacNeille as the voice.

The Simpsons, which began in 1989, had recently announced it planned to end the life of a veteran character. Producers previously killed off Ned Flanders’ wife Maude in 2000. But Jean said today that Mrs. Krabappel was not one they had planned to eliminate. “Earlier we had discussed a potential storyline in which a character passed away,” Jean said. “This was not Marcia’s Edna Krabappel. Marcia’s passing is unrelated and again, a terrible loss for all who had the pleasure of knowing her.”

Reps for The Simpsons said they were aware, however, that Wallace had become gravely ill, although her exact cause of death was not revealed. The news of her death began to spread virally on Twitter late Friday after a friend, comedian and radio host Frank DeCaro, broke the news. Grief over her loss was also tweeted by several other friends, including Yeardly Smith, who voices Lisa Simpson and Cathryn Michon, who directed her in the upcoming movie Muffin Top.

Wallace’s work as the cynical, abused, and sarcastic Mrs. Krabappel won her an Emmy for outstanding voice actress in 1992, and was nominated for outstanding guest actress in a comedy for Murphy Brown, playing the most efficient of the journalist’s constantly changing secretaries — reprising her role as Carol Kester. Adding to the joke, Newhart also made an appearance on that episode.

Born and raised in Creston, Iowa, the daughter of a shopkeeper, she moved to New York after college to pursue stage acting. She started her onscreen career making regular appearances on The Merv Griffin Show, and in 1971 had bit parts on Bewitched, Columbo, and The Brady Bunch.

A year later, The Bob Newhart Show made her a star. Her flame-haired, feisty, and free-spirited receptionist was a counterpoint to Newhart’s buttoned-down psychiatrist. She played the role of Carol Kester in 139 episodes from 1972-1978.

After that, Wallace became a regular on a litany of gameshows such as Match Game, Hollywood Squares, and The $25,000 Pyramid. She guest starred on single episodes of Magnum, P.I., Gimme a Break!, and Murder, She Wrote, among many others, and had a recurring role as Mrs. Caruthers on Full House. She also had a small role in the 1989 film Teen Witch and became a popular voice-over actress in animated shows, playing characters on Darkwing Duck and Captain Planet and the Planeteers. Later, she also co-starred as the housekeeper on the short-lived 2001 Comedy Central spoof of President George W. Bush That’s My Bush!

But it was the droll, chain-smoking, semi-defeated Edna Krabappel on The Simpsons that would give Wallace her defining role. Originally set up as a Nurse Ratched-like nemesis of trouble student Bart Simpson, she evolved into one of the richest, and most nuanced characters on the series.

In episode 16 of season 3, “Bart the Lover,” the showrunners turned a sympathetic focus on the character. Bart discovers the lonely teacher had posted a personal ad, so he begins writing her bogus love letters, accompanied by a photo of hockey star Gordie Howe. After setting her up on a fake date, he cackles to himself as he looks in the restaurant window and sees her sitting by herself. When she’s still sitting there hours later, he’s no longer so amused by his prank and sets about trying to make it right.

This was the episode that won Wallace her Emmy.

The actress was diagnosed with breast cancer in 1985 but fought it back and became a prominent activist and advocate for early detection procedures. In 2007, she won the Gilda Radner Courage Award from Roswell Park Cancer Institute for her decades of work for the cause.

She was married for six years to hotel owner Dennis Hawley, until his death in 1992 from pancreatic cancer. The couple had one son, Michael Hawley, and Wallace wrote about her illness, the loss of her husband, and the challenges of motherhood in her 2004 autobiography Don’t Look Back, We’re Not Going That Way. Despite tackling dark issues, readers acclaimed the book for its sense of humor and optimism.

The subtitle for the book was “How I overcame a rocky childhood, a nervous breakdown, breast cancer, widowhood, fat, fire and menopausal motherhood and still manage to count my lucky chickens.”

Given her love of a laugh, there may be no better way to remember her than this: