RIP Mrs Krabappel

(CNN) -- Marcia Wallace, whose four-decade television career included playing the receptionist on "The Bob Newhart Show" and Bart's fourth-grade teacher on "The Simpsons," has died, her agent said Saturday.

Wallace was 70, according to imdb.com. Her cause of death was not immediately confirmed.

Wallace starred for six seasons as Carol Kester on "The Bob Newhart Show" in the 1970s and reprised the role in the 1990s on "Murphy Brown."

But it was her Emmy-winning role as Edna Krabappel, Bart Simpson's teacher with the snarky laugh, that may have earned her the most fame in recent years. It was a part she held since the show's premiere in 1990.