Lucy Chet Devito, the daughter of Devito and Cheers actress Rhea Perlman, has made two cameos in the show to date (via IMDb). The first is in season two's "Mac Bangs Dennis' Mom." In the scene, Frank eyes his waitress, Jenny, played by his daughter, Lucy, after commenting that his date is too old for him. Lucy is billed as having a third appearance in the season two finale but doesn't appear on-screen.
So far her biggest role in the show came in season three's "Dumpster Baby", as a young woman who comments that the baby Mac and Dee found in a dumpster is cute enough to be a Gerber baby, prompting the pair to pursue a modeling career for the infant.
Taking after her thespian parents, Lucy is a film and television actress. She's starred in Disney's Melissa and Joey, appeared in The Marvelous Mrs. Maisel as Irene, and is set to appear in the upcoming film based on Marilyn Monroe's life, Blonde, alongside Ana de Armas and Adrien Brody.
