The Citadel may refer to:

• Citadel (level) - One of the Halo 3 DLC maps.
• Covenant citadel - The Covenant structure used in Halo Wars.
• Citadel (Forerunner) - The Forerunner structure located on the Ark.
• Battle of the Citadel - The last major battle to be fought in the Human-Covenant war.
• The Citadel Skull achievement - Claimed by obtaining the Citadel Skull.

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