Lynne Marie Stewart, the star of “Pee-wee’s Playhouse” opposite Paul Reubens, died at 78 on Friday.

The actress passed suddenly after a tumor was found near her liver and gallbladder in mid-December, Stewart’s representative Bette Smith told USA TODAY Saturday. Stewart had been struggling with exhaustion before the diagnosis, Smith said.

“This was totally unexpected, and she passed a month or so after her diagnosis,” Smith said.

“Lynne was the most wonderful actress. She was the kindest and (most) honorable person,” Smith added, saying the actress “loved the craft” and “didn’t care” about receiving “pay or press.”

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The Los Angeles native rose to fame with her starring role on “Pee-wee Playhouse,” opposite Reubens, playing Miss Yvonne, The Most Beautiful Woman in Puppetland, from 1986 to 1990. Reubens died at 70 after a cancer battle in July 2023.

However, her love of acting was found earlier as a student at Beverly Hills High School and later at L. A. City College where she majored in theater arts, where she met best friend Cindy Williams of “Laverne & Shirley” fame. Later, she honed her comedy skills alongside other genre heavyweights, including Reubens, at Los Angeles sketch comedy troupe and school The Groundlings, where she was a proud alum.

Since 2005, Stewart has starred as mom Bonnie Kelly, the mom of actor Charlie Day’s character of the same first name, on the beloved FX sitcom “It’s Always Sunny in Philadelphia.”

The comedic actress also made appearances in several “Pee-wee” franchise projects, the 1973 film “American Graffiti,” 2003 movie “Tracey Ullman in the Trailer Tales” and 2011’s “Bridesmaids.”

A dedicated animal advocate, she also starred in 1987’s “The Running Man,” “Clear and Present Danger” in 1994 and 1999’s “Pirates of Silicon Valley.’ According to her rep Smith, she recently wrapped work on forthcoming pickleball film “The Dink,” which stars Ben Stiller.

Stewart’s death was first shared widely by Stewart’s friend, the “Elvira” actress Cassandra Peterson, who took to Instagram to pay tribute to the late actress Friday in a post shared with her 1.5 million Instagram followers.

“My heart is breaking upon hearing the news of my dear friend @lynnestewart78 Lynne Stewart’s passing,” Peterson wrote in the post’s caption. “One of the kindest, sweetest, funniest women who ever lived. The iconic Miss Yvonne of Pee-wee’s Playhouse: She’ll always be ‘the most beautiful woman in Puppetland.'”