Bad Luck may refer to:

• Harmful or negative luck
• Bad Luck (film), a 1960 film directed by Andrzej Munk
• "Bad Luck" (Harold Melvin & the Blue Notes song)
• "Bad Luck" (Social Distortion song)
• Bad Luck, an album by Trophy Scars
• Bad Luck, a band consisting of the main characters in the manga/anime Gravitation

Luck or fortunity is good fortune which occurs beyond one's control, without regard to one's will, intention, or desired result. There are at least two senses people usually mean when they use the term, the prescriptive sense and the descriptive sense. In the prescriptive sense, luck is the supernatural and deterministic concept that there are forces (e.g. gods or spirits) which prescribe that certain events occur very much the way the laws of physics will prescribe that certain events occur. It is the prescriptive sense that people mean when they state that they "do not believe in luck". In the descriptive sense, luck is merely a name we give to events after they occur which we find to be fortuitous and perhaps improbable.