Yes, bosses. A list of them would come in handy, wouldn't it?
This thread will contain
only the bosses of the released versions, however. For future bosses, you're best checking the thread with the "future versions" thing.
Xyz: uses Omega's AI. A piece of cake with level 3 Invidia. The boss of the Entrance area. Defeating it unlocks the Life Pot item, though you need to have met the two witches in the Laboratory to access it.
Sycor: uses the Undead Core's battle AI. Not so easy as Xyz, but still beatable. The boss of the Laboratory area. Defeating it triggers a trap in the next room, but also unlocks one of two "gates" to the Map System.