A Shadow Government is a "government in waiting" that remains in waiting with the intent to take control of the government in response to some event.

In parliamentary governments it is common for the opposition party to have a shadow government in which top leaders of the opposition are prepared to assume certain ministries should the opposition come to power.

It is also used as a somewhat pejorative term to denote a government that takes over in the event of a disaster. The concept is popular in many conspiracy theories.

United States:

United Kingdom:
  • The Civil Contingencies Secretariat is responsible for planning for government continuity in the event of catastrophe, although it is not itself a "shadow government".