Sheridan also appeared on the television show "Alf" as the eccentric neighbor Mrs. Ochmonek and appeared in 12 Broadway shows.
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Her manager, Amanda Hendon, says Sheridan "was always very grateful to her fans and felt blessed to have enjoyed decades of work in the entertainment business."
Elizabeth Ann Sheridan was also a veteran stage actress with a dozen Broadway shows to her name, including appearing in "Happy End" with Meryl Streep in 1977.
She also performed in a one-woman show called "Mrs. Seinfeld sings."
In a tweet Friday, Jerry Seinfeld said, "Liz was always the sweetest, nicest TV mom a son could wish for. Every time she came on our show it was the coziest feeling for me. So lucky to have known her."
In 2000, Sheridan published a book, "Dizzy and Jimmy" about her relationship with actor James Dean.
Sheridan died in her sleep around 2:30 a.m. Friday, Hendon said.
Sheridan is survived by her daughter and son-in-law.
Her death comes just two weeks after her former co-star Estelle Harris, who played George's mother on "Seinfeld," also died at age 93.
RELATED: Estelle Harris, 'Seinfeld' and 'Toy Story' actor, dies at 93
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Estelle Harris, 'Seinfeld' and 'Toy Story' actor, dies at 93