Actress Lynne Marie Stewart, best known for her supporting roles in iconic television shows and films, died Friday, according to Variety. She was 78.

“My heart is breaking upon hearing the news of my dear friend Lynne Stewart’s passing,” said her friend, actress Cassandra Peterson in an Instagram post confirming her death.

“One of the kindest, sweetest, funniest women who ever lived,” Peterson, best known for her persona Elvira, Mistress of the Dark, said. “The iconic Miss Yvonne of ‘Pee-wee’s Playhouse:’ She’ll always be ‘the most beautiful woman in Puppetland.’”

The Los Angeles native began her career as part of the sketch comedy group “The Groundlings” where she met Peterson and comedian Paul “Pee-wee” Reubens.

She starred as Miss Yvonne, “the Most Beautiful Woman in Puppetland,” in the 1981 Broadway original show “The Pee-Wee Herman Show” and continuing in the role for nearly a decade. She starred in five seasons of television’s “Pee-wee’s Playhouse” and the two feature films, “Pee-wee’s Big Adventure and Big Top Pee-Wee.”

She also had a recurring role as the mother of Charlie Kelly (played by actor Charlie Day) on “It’s Always Sunny in Philadelphia.

Day posted an Instagram reel of Stewart from “It’s Always Sunny.” Written on the reel is “RIP TV Mom. Thanks for 20 years of laughs. You deserve a standing ovation.” The caption of the post reads, “The brilliant and talented Lynne Marie Stewart. Rest in peace. Thank you for all the years of laughter.”

Actress Laraine Newman said in an Instagram post that “the most beautiful girl in Puppetland has left us.”

“Lynne Stewart was truly an angel and brilliantly funny and an important part of our Groundlings family. As my sister said ‘if you don’t love Lynne, you’re just wrong,‘” Newman said in the post.

Her career spanned decades, from playing nurses in M*A*S*H, to recurring roles on “Laverne & Shirley.” She appeared as a driver in “American Graffiti” and had a brief role in the Arnold Schwarzenegger sci-fi thriller “The Running Man.”