Actress Liz Sheridan, who played Jerry Seinfeld’s mother on the 90s sit-com Seinfeld, died early Friday of natural causes at the age of 93, The Washington Post reported.

“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,” her TV son wrote on Twitter.

“Oh my Lord, just learning of the passing of Liz Sheridan. She was as gracious and graceful a person and actress as you’ll ever meet. Fascinating life. Wonderful lady. Rest well,” tweeted Jason Alexander, who played George Costanza on the show.

Aside from Seinfeld, Sheridan was known for her work on Broadway and her romantic relationship with actor James Dean in the early 1950s, according to The New York Post.

Sheridan is the second prominent Seinfeld alum to pass away this month. On April 2, Estelle Harris, who played George’s mother, died in Palm Desert, California. She was also 93.