Frances Joan Brill (born September 30, 1946) is a retired American actress and puppeteer, best known for her roles on Sesame Street, as well as playing Sally Hayes in the Hal Ashby film Being There (1979), Dana Mardukas in the Martin Brest film Midnight Run (1988) and Lily Marvin in the Frank Oz film What About Bob? (1991).
Brill was born in Chester, Pennsylvania, the daughter of Linette and Joseph M. Brill. Her father was a physician. She is a graduate of Boston University College of Fine Arts.
She began her career in theater, making her Broadway debut in the 1969 play Red, White and Maddox. Her other theatrical roles include leads at the Roundabout Theatre, Manhattan Theater Club, Playwrights Horizons and many regional theaters including the Long Wharf, Yale Repertory Theatre, Arena Stage, the Mark Taper Forum and the Actors Theatre of Louisville. She has been nominated twice for a Drama Desk Award, for What Every Woman Knows (1976) and for Knuckle (1981), respectively.