Madhouse (originally titled There Was a Little Girl and also known as And When She Was Bad) is a 1981 Italian slasher film directed and co-written by Ovidio G. Assonitis, and starring Trish Everly, Dennis Robertson, Allison Biggers, and Michael Macrae. The plot follows a schoolteacher in Savannah, Georgia being stalked by her psychopathic twin sister in the days leading up to their birthday. The film's original title takes its name from a poem called There Was a Little Girl by Henry Wadsworth Longfellow.

The film features a musical score by Riz Ortolani and cinematography by Assonitis regular Roberto D'Ettorre Piazzoli. Though it received theatrical distribution in Italy, West Germany, and the United States, it was one of the many films on the "video nasty" list, a list of horror and exploitation films banned in the United Kingdom by the BBFC in the 1980s for violence and obscenity.