It’s Always Sunny star Lynne Marie Stewart has died

The actress was a former member of iconic sketch comedy troupe The Groundlings.

The news of her death was announced by the star's close friend Cassandra Peterson.

Peterson, best known for her portrayal of the horror hostess character Elvira. announced the heartbreaking news in an Instagram post.

She wrote in the caption: "My heart is breaking upon hearing the news of my dear friend Lynne Stewart’s passing.

"One of the kindest, sweetest, funniest women who ever lived," Peterson added. "The iconic Miss Yvonne of Pee-wee’s Playhouse. She’ll always be 'the most beautiful woman in Puppetland'."

Stewart rose to fame as a member of The Groundlings in the 1970s.

In 1973, she had a small role in George Lucas' breakthrough movie American Graffiti, before appearing in several films and TV shows in her long career.

The actress is perhaps most recognised for her appearance in a variety of Pee-Wee Herman shows as Miss Yvonne.

She first played the part in the 1981 stage show The Pee-wee Herman Show. She continued the role during the CBS show Pee-wee’s Playhouse, before also featuring in the 2010 stage revival and Broadway production.

Stewart also had parts in all three Pee-wee Herman films.

Her more recent well-recognised role was as Charlie Kenny’s mother Bonnie, in the hit comedy series It’s Always Sunny in Philadelphia. 

This was also Stewart's last credited acting appearance, per IMDB.

Tributes have been paid to the actress on social media.  

Emmy winner Danny Deraney was among those sharing heartfelt messages, writing: "Just got word that the most beautiful girl in puppet land has passed away.

"Millions of us loved Lynne Marie Stewart who played Miss Yvonne on Pee Wee's Playhouse," she added. "Not only a groundlings legend, but truly an actor that could do anything."

Saturday Night Live star Maya Rudolph posted on her Instagram Stories a signed photo from Stewart in honor of the late actress following the news of her death.