Dorothy Zbornak (née Petrillo) was raised in Brooklyn, New York by her mother Sophia and her father Salvatore (played in flashbacks by Sid Melton and Kyle T. Heffner). Nicknamed "Pussycat" by her mother, Dorothy had a younger brother and sister. Her brother Phil, a cross-dresser, was never seen on the show. Her sister Gloria, the youngest Petrillo, married into money; she appeared in two episodes, but was played by two different actresses (Doris Belack and Dena Dietrich). After moving to Miami in her later years, Dorothy continued working as a substitute teacher.
A few weeks after their high school prom, Stanley Zbornak got Dorothy pregnant and married her to legitimize the baby. Stan and Dorothy were married for 38 years, although Stan cheated on her numerous times. He eventually left her for a young flight attendant named Chrissy, whom he met on the way to a business conference in Hawaii. Dorothy had two children, Kate and Michael.
Though Dorothy and Stan were divorced, he made numerous appearances on the show (the character of Stan was portrayed by Herb Edelman), usually running to Dorothy whenever something went wrong in his life. Every time he visited her, he always opened with the line "Hi...it's me, Stan". Stan continued to see Dorothy as a comforting, reliable figure, even though he was the one who destroyed their marriage.
In the series' final episode, Dorothy married Blanche's uncle, Lucas Hollingsworth (played by Leslie Nielsen). Stan, though saddened to see Dorothy move on to her new life without him, gave Dorothy his blessing while disguised as the limo driver who took her to the wedding. Blanche, Rose and Sophia were saddened about Dorothy leaving, but she assured them that she would visit often and that no matter what, they would always be family. The episode ended when Dorothy left and the three remaining roommates hugged.