Black Flag or black flag may refer to:

• The Black Standard, a legendary flag in Islamic tradition
• The Anarchist black flag
• The Jolly Roger, flag associated with piracy
• The Pan-African flag, a trans-national unity symbol
• Black flag (racing)

• Black Flag (band), an American hardcore punk band
• Black Flag (comics), a comic book superhero team from Maximum Press
• Black Flag (Ektomorf album), a 2012 album by Ektomorf
• Black Flag (Machine Gun Kelly mixtape), 2013
• "Black Flag" (song), a 1992 song by King's X
• Black Flag (newspaper), a publication in Britain
• Assassin's Creed IV: Black Flag, 2013 videogame by Ubisoft
• Black Flags: The Rise of ISIS, a 2015 Pulitzer prize-winning book by Joby Warrick

• Black Flag, Western Australia, an abandoned town named after the Black Flag gold mine and farm

• Ali Charaf Damache, a terror suspect with the nom de guerre "the Black Flag"
• Black Flag (insecticide)
• Black Flag Army, a militia in Vietnam and southern China, 1860s-1885
• Chernoe Znamia, a 20th-century Russian anarchist organisation
• Ferraria crispa, a plant also known as black flag