Bosses are enemies with a health bar and have a pattern of attacks or stages of attacks. They are often fought in an enclosed space that the player cannot exit until they defeat the boss.
Bosses are listed by order of appearance in the game.
|Balrog||Mimiga Village, Bushlands, Labyrinth|| The Mimiga Village battle is optional.|
Fought twice in Bushlands; the second time as Balfrog.
|Igor||Egg Corridor||Captures Sue. Also appears as a basic enemy on the Balcony.|
|Balfrog||Gum||Balrog when transformed by Misery to a frog-like monster.|
|Curly Brace||Sand Zone||Guards the Sand Zone Residence.|
|Omega||Sand Zone||Required to move the Sun Stones.|
|Rabid Toroko||Warehouse||Toroko, fed with Red flowers by Doctor.|
|Pooh Black||Clinic Ruins||Required to pick up the Cure-All|
|Monster X||End of Labyrinth W||When defeated transforms to a cat|
|Core||Core area||Core of the island. Fought with Curly Brace|
|Ironhead||Main Artery||If defeated without taking damage, the player receives the Alien Medal.|
|Sisters||Egg Observation Room?||They are an optional boss fight. Collecting the missile expansion is required in order to summon them.|
|Ma Pignon||Storage Room||Required in order to return Curly's memory|
|Red Ogre||Last Cave Hidden||The player receives the Medal of the Red Ogre after defeating this boss.|
|Muscle Doctor||King's Table||The second form of the Doctor.|
|Undead Core||Black Space||The risen core of the island.|
|Heavy Press||Blood Stained Sanctuary||Found at the end of B3 of the Blood Stained Sanctuary.|
|Ballos||Seal Chamber||Final boss of the game.|
- Up to nine boss battles can be skipped if the Sisters and first Balrog battle are avoided, and the bad ending is attained.
- The only two Bosses that drop Exp. Crystals when defeated are the first Balrog and the Red Ogre.