Lynne Marie Stewart , best known for her role as Miss Yvonne in Pee-wee’s Playhouse , has passed away at the age of 78. The actress died suddenly on Friday after being diagnosed with a tumor near her liver and gallbladder in mid-December.

Her representative, Bette Smith, confirmed the news to USA TODAY, revealing that Lynne Marie Stewart had experienced extreme exhaustion in the weeks leading up to her diagnosis. Talking to the media, Bette said, “This was totally unexpected, and she passed a month or so after her diagnosis. Lynne was the most wonderful actress. She was the kindest and (most) honorable person.”

Born in Los Angeles, Lynne Marie Stewart’s love for acting blossomed early. She studied theatre arts at L.A. City College, where she formed a lifelong friendship with Laverne & Shirley star Cindy Williams. She later honed her comedic skills at The Groundlings, the legendary Los Angeles sketch troupe, where she trained alongside industry greats, including Paul Reubens.
From 1986 to 1990, Lynne Marie Stewart brought to life the charmingly eccentric Miss Yvonne, dubbed "The Most Beautiful Woman in Puppetland," in Pee-wee’s Playhouse, a role that made her a household name. In later years, she became widely recognized as Bonnie Kelly, the hilariously oblivious mother of Charlie Day’s character in It’s Always Sunny in Philadelphia , a recurring role she played since 2005.
Beyond these beloved roles, Lynne Marie Stewart enjoyed a prolific career in film and television. She appeared in American Graffiti (1973), Tracey Ullman in the Trailer Tales (2003), and Bridesmaids (2011), among many others.
Meanwhile, her previous outing was in the TV series ‘AJ and the Queen’, in which she played the character Florence in one of the episodes. She has also lent voice to a pivotal character named Sister Agnes in the TV series ‘Mike Tyson Mysteries’.