The Secret of the Black Widow () is a 1963 West German crime film directed by Franz Josef Gottlieb and starring O. W. Fischer, Karin Dor and Klaus Kinski. It is part of a boom of Krimi films produced during the decade, the third of four films based on the work of Louis Weinert-Wilton that came in the wake of Rialto Film's successful Edgar Wallace adaptations. It was shot in Spain. The film's sets were designed by the art director Ramiro Gómez.