Dissidia Final Fantasy is a fighting game developed and published by Square Enix for the Sony PSP for the Final Fantasy series 20th anniversary. The game was first announced at the "Square Enix Party" event of May 2007.

The two gods within Dissidia, Cosmos, the goddess of harmony, and Chaos, the god of destruction have warred for centuries until the balance of power tips in favor of Chaos. As the forces of evil grow stronger and the war is nearing its end, a few remaining survivors band together to fight Chaos and restore harmony.

The game reunites characters from throughout the Final Fantasy series as well as new characters, such as Cosmos, the goddess of harmony. The storyline requires that players assume the role of all 22 of the playable characters at some point throughout the game in order to successfully complete it. Each of the eleven heroes and eleven villains represents a game from Final Fantasy through Final Fantasy X, with the two secret characters representing Final Fantasy XI and Final Fantasy XII.

Most of the characters can transform into various forms as part of their EX modes. Each character has an alternate costume, and the characters' equipment is customizable. They increase EXP and gil from winning battles.

The fifty different summons each have different effects and are accessible using Summon Stones.