Final boss theme

"Final Boss" is a recurring track in the Final Fantasy series. The Final Boss theme is obviously used for the final boss of the game. Some Final Boss themes are named for the boss, while others have unique names. Many are simply titled "The Final Battle" or "Battle to the Death".

Final Fantasy
The original releases of the game had no boss theme of any kind, and so the battle with Chaos used the normal battle theme. However, in the Origins, Dawn of Souls and Anniversary remakes, the theme is called "Last Battle".

Final Fantasy II
In the original NES release, The Emperor used the same boss theme as all other bosses, called "Battle Scene 2". However, in every remake after the PS one, a second boss theme was made for normal bosses, and "Battle Scene 2" was used as the final battle theme.

Final Fantasy III
The theme plays during the battle with the Cloud of Darkness. In some remixes of the theme on soundtracks, the theme is titled "Kurayaminokumo", which literally translates into English as "Cloud of Darkness".

Final Fantasy IV
The theme plays during the battle with Zeromus. In the second album with The Black Mages, the theme is titled "Zeromus".

Zeromus is reused in Final Fantasy IV: The After Years during the battle with Zeromus's Malice.

Final Fantasy IV: The After Years
Three songs play during the final battle with the Creator. One is for the first phase of the fight which is against the Creator's core, and also his third form. The other, which occurs in the second battle, is the theme used for the Depths (which is a remix of the Maenad's theme). The last plays for the Creator's final form.

Final Fantasy V
The theme is used during the battle with Neo Exdeath. In the third album by The Black Mages, it is retitled "Neo Exdeath".

Final Fantasy VI
The first final boss theme to have its own specific name, Dancing Mad is divided into four parts, each of which plays during the battle with one of the tiers of enemies leading up to Kefka, the final boss of the game. Remixes of several other themes from throughout the game are spliced into the overarching theme.

Final Fantasy VII
The final boss theme used for the fight with Safer Sephiroth, it has since become the signature theme of Sephiroth himself. It has been remixed many times since its original appearance for Sephiroth's various appearances outside of Final Fantasy VII.

Crisis Core -Final Fantasy VII-
"SOLDIER Battle" plays during the final battle with Genesis.

Final Fantasy VIII
Played during the final battle with Ultimecia, "The Extreme" incorporates Fithos Lusec Wecos Vinosec into its opening. The track was rearranged by the Black Mages for their third studio album, The Black Mages III: Darkness and Starlight.

Final Fantasy IX
Played during the battle with Necron.

Final Fantasy X
Technically, the final boss of Final Fantasy X is Yu Yevon, and he has his own theme "Decisive Battle". However, due to Yu Yevon being notoriously easy to defeat, Braska's Final Aeon is widely considered the true final boss of the game. The song that plays during the battle is Otherworld, which also plays during the opening FMV of the game.

Final Fantasy XII
Originally played during the battle with The Undying, the Battle for Freedom is also used as the final boss theme for the Final Fantasy XII spin-off, Revenant Wings. The piece incorporates variations of the themes used throughout the game's soundtrack, particularly those in the Theme of the Empire.

Final Fantasy Tactics
Played during the battle with Ultima. In the PSP release, it is retitled "The Heartless Hellion".

Final Fantasy Tactics Advance
Played during the battle with Li-Grim.

Dissidia Final Fantasy
Played during the battle with Chaos. Though the theme is one continuous piece, it is segmented into three when used in-game, and each portion is used for one of the three battles with Chaos.

Several (but not all) final boss themes from previous games are also available as music choices to be heard in battles. Some of the final boss themes are already available, others must be purchased in the PP Catalog

Final Fantasy Crystal Chronicles
Fusion, Descent is played during the final battle against Raem.

Final Fantasy Crystal Chronicles: Ring of Fates
Galdes Battle is played in the final battle against Great Galdes.

Final Fantasy Crystal Chronicles: Echoes of Time
Last Battle is played in the final battle against Larkeicus.