The underworld is a place in religion and mythology to where the souls of the recently departed go.

Underworld may also refer to:

• Greek underworld, the Greek version
• Criminal underworld, another name for organized crime
• Hell in Christianity, sometimes used more favorably than "hell"

• Underworld (comic strip), an adult comic strip by Kaz
• Underworld (Mad Cave Studios comics), a 2024 comic by Mad Cave Studios

• Tomb Raider: Underworld, released in 2008, the eighth game in the Tomb Raider series
• Ultima Underworld, series of computer games first released in 1992
• Underworld: The Eternal War, a 2004 PlayStation 2 game based on the 2003 film
• Underwurlde, 1984 computer game featuring Sabreman

• Underworld (1927 film), a silent film directed by Josef von Sternberg
• Underworld (1937 film), an Oscar Micheaux film
• Underworld (1985 film), a horror film written by Clive Barker
• Underworld (1996 film), a comedy/thriller film starring Denis Leary and Joe Mantegna
• Underworld (film series), a horror/action film series with five installments
  • Underworld (2003 film), the first movie, released in 2003
  • Underworld: Evolution, the 2006 sequel
  • Underworld: Rise of the Lycans, the 2009 prequel
  • Underworld: Awakening, 2012, fourth movie in the series
  • Underworld: Blood Wars, 2016, fifth movie in the series
• Underworld (2003 film), a 2003 Bangladeshi film, featuring Shakib Khan
• Underworld (2004 film), a 2004 Sri Lankan film
• Underworld (Doctor Who), a serial in the British science fiction television series Doctor Who
• Underworld Trilogy, 2010 drama/thriller television series
• Cities of the Underworld, a documentary television series

• Underworld (novel), a 1997 novel written by Don DeLillo
• Underworld: The Mysterious Origins of Civilization, a non-fiction work of historical speculation written by Graham Hancock
• Resident Evil: Underworld, the fourth entry in S.D. Perry's series of novels based on Capcom's franchise of videogames, Resident Evil
• Underworld (Reginald Hill novel), a 1988 novel from the Dalziel and Pascoe series
• Underworld (Doctor Who novel), novelization of the television episode
• Underworld (film series novels), novelizations of the Underworld film series and an original novel based on the setting

• Underworld (band), a British electronic music band
• Underworld (Adagio album), a 2003 album
• Underworld (Divinyls album), a 1996 album
• Underworld (Symphony X album), a 2015 album
• Underworld (Vamps album), a 2017 album
• Underworld (Tonight Alive album), a 2018 album
• Camden Underworld, a music venue and nightclub located under The World's End pub in Camden Town, London

• Netherworld (disambiguation)
• Hollow Earth (disambiguation)