Underworld has a number of meanings

• In mythology and religion, the underworld is a generic term, referring to any place to which newly dead souls go.
• The term underworld is sometimes used to describe organized crime.
• Underworld is the name of an electronic band.
• Underworld is the name of a comic strip by the artist Kaz.
• Underworld is a novel by American writer, Don DeLillo.
• Underworld is the name of a 1936 film produced and directed by Oscar Micheaux.
• Underworld is the name of a 1986 movie.
• Underworld is the name of a 2003 movie starring Kate Beckinsale.