The Cataclysm (大崩壊, Dai Hōkai?) is an event in Ivalice history mentioned several times in Final Fantasy Tactics. It was a catastrophic disaster that ruined kingdoms and killed many beings, though its exact nature is unknown. It is unknown when it took place or how long it endured, though it occurred less than 1200 years prior to Final Fantasy Tactics.

The Cataclysm is mentioned by name in the Japanese version of Final Fantasy Tactics and in The War of the Lions. The term was absent from the original English translation, being interpreted instead as a variety of different disasters.

It is mentioned most commonly in the descriptions of the wonders, and is credited with great destruction. At least one errand also speaks of it, revealing that, according to legend, humanity was saved from its effects by the Hero-King Mesa.

The Cataclysm is often assumed to be the cause behind the loss of Ivalice's most advanced technologies, though the game never outright states this. It also destroyed at least two races, the "winged ones" (possibly the aegyl), the moogles (as stated in the Siedge Weald) and the Clockwork City of Goug, and, if the Ivalician myth is true, threatened humanity, leading some to believe it is responsible for the disappearance of the non-hume races from Ivalice. The sinking of Mullonde, occurring at the end of Ajora's life and involving the drowning of an entire state of the Ivalician peninsula, may also relate to it. The Cataclysm created the Floating Continent, and destroyed Eureka and of the Fortress of Trials.

As the Cataclysm has only been referred to in the context of other events, however, it remains largely mysterious.