Mitchell, who was believed to be the last surviving adult castmember from the legendary CBS sitcom, died November 11 of heart failure at her condominium in Westwood, her sister-in-law, the Oscar-nominated Sunset Blvd. actress Nancy Olson, told The Hollywood Reporter.
Mitchell joined the cast of Lucille Ball's I LOVE LUCY for the 1953-54 season and appeared in three episodes. In one, “Lucy Tells the Truth,” Marion gets frank opinions about her new hat and her laugh during the girls’ weekly bridge game. (Lucy has bet Fred and Ethel Mertz $100 that she can go 24 hours without telling a lie.)