Nightmare

Nightmare may refer to:
 * A special ability of Diablos in Final Fantasy XI, which inflicts both bio and sleep status effects on all player characters within range.
 * An enemy from Final Fantasy XII.
 * A spell used by Queklain and Zalera from Final Fantasy Tactics.
 * A Corner skill learned by Assassins in Final Fantasy Tactics Advance.
 * An enemy type from Final Fantasy Mystic Quest.