Black widow may refer to:

• The black widow spider, Latrodectus mactans
• A typology of female serial killers
• The Northrop P-61 Black Widow, an American night fighter aircraft used in World War II
• The Northrop/McDonnell Douglas YF-23 Black Widow II, a prototype fighter aircraft designed to compete with the F-22 Raptor
• Black Widow, a 1954 film starring Ginger Rogers, Van Heflin, Gene Tierney, and George Raft, with Peggy Ann Garner, about a woman murderer
• Black Widow, a 1987 film starring Debra Winger, Theresa Russell, Sami Frey, and Dennis Hopper, about a woman who murders the men she marries for their money
• Black Widow, a 2005 film starring Sarah Slean, Mary Margaret O'Hara and Martin Tielli, loosely based on the life of Evelyn Dick
• A Novel, a 1981 novel by Christina Crawford
• Black Widowers, a fictional men-only dining club created by Isaac Asimov for a series of mystery stories starting in 1971
• Black Widow (comics), two fictional comic book spies in Marvel Comics
• Black Widow (Golden Age), a comic book character from Marvel Comics' 1940s precursor, Timely Comics
• Black Widow (arcade game), a 1982 Atari arcade game
• Black Widow (band), an obscure early 1970s British progressive rock band
• A girl dressed all in black accompanied by a man in a Zoot Suit
• The nickname of Jeanette Lee, a pool player who tends to dress in black
• The nickname of Sonya Thomas, a champion competitive eater
• The Black Widows, a Chechen rebel group
• "The Black Widow", a song by Alice Cooper on his album Welcome to My Nightmare
• "Black Widow", a song by the rock band Mötley Crüe on the compilation Red, White and Crüe
• Black Widow (Slam Masters), a character from the Slam Masters/Muscle Bomber series of games by Capcom
• Black Widow Cheer Gym, an all-star cheerleading facility in Ottawa, Canada
• The black widow, Stygnobrotula latebricola, a species of brotula
• Black Widow A Canadian made Motion Picture.