In Hades, we explore Greek mythology by travelling through different biomes and fighting various bosses. Zagreus would fight and defeat them in the following order:

1. In Tartarus: one of the Fury Sister, Megaera (or even all 3 of them when Extreme Measures is enabled)
2. In Asphodel: the Bone Hydra
3. In Elysium: Theseus, the former king of Athens, and Asterius, the Minotaur
4. In Temple of Styx: Ceberus, the three headed hell hound
5. On the "Surface": Hades, the god of the Underworld