Boss Music is used numerous times in the Kingdom Hearts series to indicate that the current battle is with a boss. Most Boss Music is fast-paced and sends a theme of evil or tension. Usually the same song would be used in different boss battles to show the connection between them, i.e Shrouding Dark Cloud is associated with Heartless Bosses and Squirming Evil is used commonly for Disney Bosses in Kingdom Hearts.

Kingdom Hearts

Awakening

  • Darkside - Dive into the Heart (Destati)

Destiny Islands

Traverse Town

  • Leon - Night of Fate

Wonderland

Olympus Coliseum

  • Cloud (Story) - Shrouding Dark Cloud
  • Sephiroth - One-Winged Angel (from Final Fantasy VII)

Deep Jungle

  • Sabor - Having a Wild Time

Agrabah

  • Jafar (1st Battle) - Squirming Evil

Monstro

  • Parasite Cage (2nd Battle) - Destiny's Force

Atlantica

Halloween Town

Neverland

Hollow Bastion

  • Riku (1st Battle) - Scherzo Di Notte
  • Riku (2nd Battle) - Forze del Male

World Terminus

End of the World

  • Ansem (1st Battle) - The Deep End
  • Ansem (2nd Battle) - Forze del Male

Kingdom Hearts Final Mix

Hollow Bastion

Kingdom Hearts: Chain of Memories

Sora Mode

Traverse Town

Wonderland

Olympus Coliseum

  • Hades - The Fight for my Friends

Agrabah

  • Jafar - The Fight for my Friends

Monstro

Halloween Town

Atlantica

  • Ursula - The Fight for my Friends

Neverland

Hollow Bastion

Destiny Islands

Simulated Twilight Town

  • Vexen (2nd Battle) - The 13th Struggle

Castle Oblivion

  • Axel (1st Battle) - The 13th Struggle
  • Larxene (1st Battle) - The 13th Struggle
  • Vexen (1st Battle) - The 13th Struggle
  • Larxene (2nd Battle) - The 13th Struggle
  • Axel (2nd Battle) - The 13th Struggle

Riku Mode

Hollow Bastion

Traverse Town

Agrabah

  • Jafar - The Fight for my Friends

Monstro

Neverland

Wonderland

Olympus Coliseum

  • Hades - The Fight for my Friends

Atlantica

Halloween Town

Destiny Islands

Simulated Twilight Town

Castle Oblivion

  • Vexen - The 13th Struggle

Kingdom Hearts Re:Chain of Memories

Sora Mode

Castle Oblivion

Riku Mode

Destiny Islands

Kingdom Hearts II

Roxas

Awakening

Simulated Twilight Town

  • Axel (1st Battle) - The 13th Struggle
  • Axel (2nd Battle) - The 13th Struggle

Sora

Hollow Bastion

  • Demyx (2nd Battle) - The 13th Dilemma

Radiant Garden

  • Sephiroth - One Winged Angel (For Final Fantasy VII)

Land of Dragons

Beast's Castle

Underworld

  • Demyx (1st Battle) - Tension Rising
  • Pete (1st Battle) - Rowdy Rumble

Olympus Coliseum

  • Hydra - Desire for All That Is Lost

Timeless River

  • Pete (2nd Battle) - Rowdy Rumble
  • Pete (3rd Battle) - Desire for All That Is Lost

Port Royal

  • Grim Reaper (2nd Battle) - The Corrupted

Agrabah

Halloween Town

Christmas Town

Pride Lands

  • Scar - The Encounter

Space Paranoids

  • Sark - Sinister Shadows

The World that Never Was

Kingdom Hearts

Kingdom Hearts II Final Mix

The Gathering Place

Cavern of Remembrance

The World that Never Was

Various

  • All Absent Silhouettes - The 13th Refection (Agrabah (Vexen), Twilight Town (Lexaeus), Underworld (Zexion), Beast's Castle (Marluxia), Port Royal (Larxene))

Kingdom Hearts 358/2 Days

Twilight Town

  • Guardian - Tension Rising
  • Veil Lizard - Shrouding Dark Cloud
  • Tailbunker - Tension Rising (most minibosses have this as their music)
  • Darkside - Destiny's Force
  • Powered Armor - Tension Rising
  • Dustflier - Struggle Away
  • Xion: Final Form - Dirge of the Fourteenth

Agrabah

  • Pete - Rowdy Rumble
  • Antlion - Shrouding Dark Cloud
  • Xion: Third Form - Struggle Away

Beast's Castle

Olympus Coliseum

Wonderland

  • Lurk Lizard - Tension Rising
  • Crimson Prankster -
  • Xion: First Form - Shrouding Dark Cloud

Never Land

  • Wavecrest - Tension Rising
  • Ruler of the Sky - Struggle Away

Halloween Town

  • Leechgrave - Vim and Vigor
  • Xion: Second Form - Vim and Vigor

The World That Never Was