| Armand |  | Boss | Legovich's Arms | Optional blacksmith-shop boss in Ossex; beating Armand restores the smithy to normal operation. | View boss |
| Astromancer |  | Boss | Astral Orrery | Boss encounter in the floating Scholar installation above Tenebrous Isle. | View boss |
| Dark Deluxy |  | Boss | Windy Generator | Optional fight sealed by Spark slots and triggered by escorting Luxy back through the door. | View boss |
| Dugin |  | Boss | Southern Outskirts | Randomized rabbit-shaped fight; beat it twice for the Lace Glove trinket. | View boss |
| Evra The Undying |  | Boss | Goddred's Grave | Secret skeleton-summoning boss riding a massive undead steed. | View boss |
| Frozen Horror |  | Boss | Coltrane Peak | Spark Generator boss for Coltrane Peak. | View boss |
| Furgus The Faithful |  | Boss | Radiant Manor | Butler boss of Radiant Manor. | View boss |
| Hulk Trooper |  | Mini-boss | Ossex | Larger, stronger Shock Trooper with wide reach. | View boss |
| Locomotress Agnes |  | Boss | Frozen Trainyard | Runaway train boss where Mina rides the cars while Agnes pursues. | View boss |
| Lumenarks |  | Boss | Astral Orrery | Cultist boss encounter in the Astral Orrery. | View boss |
| Madd House |  | Boss | Madd House | House-as-boss encounter in Papa Madd's house in Kindlewood. | View boss |
| Major Miner |  | Boss | Bone Beach | Mid-game boss encountered at Bone Beach. | View boss |
| Malady |  | Boss | Nox's Bayou | Disease- or corruption-themed boss encounter. | View boss |
| Maxi |  | Boss | Ossex | Optional ambush boss triggered by returning through the eastern road. | View boss |
| Midden |  | Boss | Ancestral Chamber | Optional Queensbury boss behind a two-Plasma-Vial door. | View boss |
| Mined Mind |  | Boss | Bone Beach | Mining-themed Bone Beach boss. | View boss |
| Mirren |  | Boss | Coltrane Peak | Ghost secret boss in Frostbite Woods tied to the Mirren NPC line. | View boss |
| Mock Moon |  | Boss | Kindlewood | Boss-room encounter in Kindlewood. | View boss |
| Nether Kraken |  | Boss | — | Optional intro encounter that awards the Uranium Bracelet. | View boss |
| Nox's Beast |  | Boss | Nox's Bayou | The enormous predator hinted at by the swamp's flavor text. | View boss |
| Orrery Warden |  | Boss | Astral Orrery | Warden patrolling the floating Scholar installation. | View boss |
| Patchling |  | Boss | Septemburg | Patchwork creature fitting the scarecrow corruption route. | View boss |
| Radiant Lionel |  | Boss | Radiant Manor | Final boss encounter in Radiant Manor's courtyard. | View boss |
| Radiant Manor |  | Boss | Astral Orrery | Architectural boss-like encounter tied to the manor framing. | View boss |
| Skullpox |  | Boss | Queensbury Crypt | Skull-themed Queensbury Crypt boss. | View boss |
| Smorgasboar |  | Boss | Septemburg | Boar-shaped Septemburg boss with feast-themed corruption flavor. | View boss |
| Sparkmancer |  | Boss | Astral Orrery | Spark-themed Astral Orrery boss. | View boss |
| Thalassion |  | Boss | Fishing Hole | Giant-fish boss tied to the fishing chain and Gilded Rod upgrade. | View boss |
| The Carving Man |  | Boss | Septemburg | Major scarecrow-corruption boss in Septemburg. | View boss |
| The Congealed |  | Boss | — | Secret-leaning encounter referenced by internal boss data. | View boss |
| The Duchess of Queensbury |  | Boss | Queensbury Crypt | End boss of Queensbury Crypt and the first major showcase fight. | View boss |
| Thorne |  | Boss | Ossex | First major boss encounter after the intro and recurring antagonist. | View boss |
| Wonder Willis |  | Boss | Music Hall | Pirate-shark secret boss at the Bowery music hall in Ossex. | View boss |
