Underground most commonly refers to:

• Subterranea (geography), the regions beneath the surface of the Earth

Underground may also refer to:

• Buenos Aires Underground, a rapid transit system
• London Underground, a rapid transit system
• The Underground (Boston), a music club in the Allston neighborhood of Boston
• The Underground (Stoke concert venue), a club/music venue based in Hanley, Stoke-on-Trent
• Underground (Manhattan), a music club (1980–1989) in Manhattan
• Underground Atlanta, a shopping and entertainment district in the Five Points neighborhood of downtown Atlanta, Georgia
• Underground City, Montreal
• Underground city, a series of linked subterranean spaces
• Underground living, modes of living below the ground's surface

• London Underground, Metro network in London

• Underground (1928 film), a drama by Anthony Asquith
• Underground (1941 film), a war drama by Vincent Sherman
• Underground (1970 film), a war drama starring Robert Goulet
• Underground (1976 film), a documentary about the radical organization the Weathermen
• Underground, a 1989 film featuring Melora Walters
• Underground (1995 film), a film by Emir Kusturica
• Underground, a 2007 British independent film starring Mark Strange
• Underground (2020 film), a/k/a Souterrain, a drama film directed by Sophie Dupuis
• Underground: The Julian Assange Story, a 2012 Australian television film on Julian Assange for Network Ten

• Underground (role-playing game), a satirical superhero game
• Underground, an expansion pack for Tom Clancy's The Division
• Medal of Honor: Underground, a 2000 first-person shooter
• Need for Speed: Underground, a 2003 racing video game
• Need for Speed: Underground 2, a 2004 racing video game
• Tony Hawk's Underground, a 2003 skateboarding video game
• Tony Hawk's Underground 2, a 2004 skateboarding video game
• Underground Zone, the first level in Sonic the Hedgehog 2 (8-bit)
• Undertale, an indie role-playing game

• Underground (Dreyfus book), a 1997 nonfiction book about computer hacking
• Underground (McGahan novel), by Andrew McGahan
• Underground (Murakami book), a 1998 collection of interviews about the Tokyo sarin gas attack
• Underground comix, small press or self-published comic books that are often socially relevant or satirical in nature
• BaMahteret (lit. Underground), a newspaper of the Lehi (militant group)
• The Underground (Animorphs), by K. A. Applegate
• The Underground (Left Behind: The Kids), by Jerry B. Jenkins and Tim LaHaye

• Underground, by Analog Pussy, 2001
• Underground (Chris Potter album), 2006
• Underground (Courtney Pine album), 1997
• Underground (The Electric Prunes album), 1967
• Underground (soundtrack), by Goran Bregović, 2000
• Underground (Graham Bonnet album), 1997
• Underground (Jayo Felony album), 1999
• Underground, by Messiah, 1994
• Underground (Phil Keaggy album), 1983
• Underground (Thelonious Monk album), 1968
• Underground (Twinkle Brothers album), 1982
• Underground Vol. 1: 1991–1994, a compilation album by Three 6 Mafia, 1999
• Underground Vol. 2: Club Memphis, a compilation album by Three 6 Mafia, 1999

• "Underground" (Ben Folds Five song), 1995
• "Underground" (David Bowie song), featured in the film Labyrinth
• "Underground" (Evermore song), 2010
• "Underground", by Adam Lambert from The Original High, 2015
• "Underground", by Circa Zero from Circus Hero, 2013
• "Underground", by Curtis Mayfield from Roots, 1970
• "Underground", by Decadence from Undergrounder, 2017
• "Underground", by Eminem from Relapse, 2009
• "Underground", by Gentle Giant from Civilian, 1980
• "Underground", by Hayley Kiyoko from Panorama, 2022
• "Underground", by Jane's Addiction from The Great Escape Artist, 2011
• "Underground", by Men at Work from Business as Usual, 1981
• "Underground", by @onefive from 1518, 2022
• "Underground", by Pokey LaFarge from Something In The Water, 2015
• "Underground", by The Tea Party from Triptych, 1999
• "Underground", by Tom Waits from Swordfishtrombones, 1983
• "The Underground", by Mani Spinx, 2008

• Underground music, a variety of music subgenres

• Underground (TV series), a 2016 American television drama series
• TCM Underground, a weekly cult-film showcase
• The Underground (TV series), a sketch comedy show
• "Underground" (Armchair Theatre), a 1958 British television drama, part of Armchair Theatre
• "Underground" (Stargate Atlantis), an episode of Stargate Atlantis
• "Underground" (BoJack Horseman), an episode of BoJack Horseman
• "Underground", a Transformers: Armada episode

• Underground (play), by Michael Sloane
• Underground press, independent counterculture publications
• Underground producciones, an Argentine producer of TV series

• Narodnaya Volya, an underground group in late 19th-century Russia
• Resistance movement
  • Resistance during World War II, with some groups sometimes referred to informally as "The Underground"
    • Polish Underground State (Polish: Polskie Państwo Podziemne), 1939-1945
• Weather Underground, a clandestine far-left terrorist group which operated in the United States of America between 1969 and 1977

• Underground economy, a market system operating outside of legal regulations
• UK underground, a counter-cultural movement in the United Kingdom
• UK underground rap, a 2020s music scene in the United Kingdom
• Underground Railroad, an informal network of secret routes and safe houses
• The Underground (roller coaster), a wooden roller coaster at Adventureland (Iowa)
• Underground mining (hard rock), removal of valuable minerals from below the Earth's surface

• Rapid transit, rail-based transportation systems, which often operate in tunnels
• Underground culture (disambiguation)
• Underground 2 (disambiguation)
• 6 Underground (disambiguation)
• Overground (disambiguation)