Civil war may refer to:

• A civil war, a conflict within a given society or nation state.
• Any particular civil war (see list of civil wars for a comprehensive list):
  • English Civil War (1642-1651)
  • American Civil War (1861-1865)
  • Russian Civil War (1918-1922)
  • Spanish Civil War (1936-1939)
  • Irish Civil War (1922-23)

Civil war may also refer to a "war-like" competition:

• Civil War (college rivalry) and Civil War (college football game), competitions between Oregon State University and the University of Oregon.
• Civil War, claimed to be a distinct variation of the drinking game Beer Pong.