Underkeep Optional Bosses: Confirmed Fights, Named Foes, and Prep Tips

If you are searching for Underkeep optional bosses, the short answer is that the game confirms the category without publishing an official roster. The Steam store page for Underkeep (app 2411200) lists "hidden alcoves, fake walls, optional bosses and puzzles," and Steam's official achievement page for the same app names two encounter anchors: a bandit chieftain and three High Clerics. A current player-written guide fills in more names, and this article labels that layer clearly as reference material. Below is everything the written record supports about Underkeep optional bosses.

The Documented State of Underkeep Optional Bosses

The official store description states the category but stops short of a roster, floor numbers, loot tables, or difficulty notes. Steam's official achievement page supplies two named encounter anchors: "Who's the Boss Now?" requires defeating the bandit chieftain, and "Silencer" requires defeating all three High Clerics. That is official evidence of named fights — it is just not a complete optional-boss list.

The next layer of evidence is Steam screenshots, which put two labels on enemy health bars: Skeleton King and Boneblade. Those are names in a picture, not statements of role, and a written review published 4 November 2026 mentions skeleton enemies and optional bosses as categories without attaching a name, a location, a weakness, or a drop to either.

The broadest current list comes from the player-written Underkeep Player's Guide on Steam Community, updated November 6, 2026. Its "Bosses and named foes" section names Rat Queen, Mother of the Warren; Arachneira; Scourge of the Tunnels; Orc Chieftain; Bandit Chieftain; Dreadcoil of the Deep; Frog King, Last Crown of the Mire; Obula; Skeleton King; Fangspire; Mud Ooze; The Thing; and "several more deeper in." That guide is not official, and it does not mark which entries are optional, so treat all of it as for reference only.

Every Name Attached to Underkeep Optional Bosses (Dated Table)

Snapshot taken 2026-11-06 from the Steam store page (app 2411200), the official achievement page, and the current player guide. The last row is included only so you can rule it out.

That bottom row saves real time. Search for boss names attached to "The Underkeep" and most results belong to the Final Fantasy XIV duty, which has its own wiki, its own mechanics, and nothing to do with the first-person crawler on Steam. Copying those fights onto a guide for this game would answer a question nobody asked.

Skeleton King and Boneblade: Current Evidence

A health bar label proves a name existed in a build. It does not prove the fight is optional, which floor it sits on, what it resists, or what it drops. The current player guide goes further than the screenshot label for Skeleton King by listing it under "Bosses and named foes," so it should no longer be described only as an unconfirmed screenshot label — but a player-written list is still reference material, not an official roster.

Boneblade has the weaker case. The player guide lists Boneblades and Boneblade Archers among early skeletons rather than in its boss section, and in a creator's recorded run of the opening dungeon "Boneblade" appears as an undead enemy label during a corridor scrap on the way to a mushroom errand. Treat it as an early enemy until a stronger source reclassifies it.

What the Demo Confirms About Optional Content

The strongest official signal is not about bosses at all. In a Steam forum thread asking whether the game would use hidden buttons and passable walls, a developer reply (thread posts dated February 27–28, captured 2026-11-06) confirmed that both exist, that hints are placed so secrets are not unfair, and that secrets are not meant to block main-story progress — in most cases they lead to optional areas or rewards. You can read the exchange in the Steam discussion on secret buttons.

Community reports add practical texture. Interactables such as berry bushes, fruit trees, tombstones, torches, and buttons are visible if you actually scan each wall, and the automap is a reliable tell for rooms you have not opened yet. Players who skip the map tend to walk past the optional content and then wonder where it went.

The demo also shows optional encounters, not just optional doors. In the creator's run, a spore-and-mushroom creature offers a peaceful resolution: hand back the mushroom caps you gathered and it rewards you with a vision and a very different transformation outcome. You can also attack it instead. That is the shape optional content takes here, and it is a reasonable mental model for how Underkeep optional bosses may be gated — behind a choice, a conversation, or a hidden wall rather than a mandatory door.

Prep That Pays Off Before Boss Fights

You cannot build a counter for a fight with no published name, but you can build a party that survives whatever sits behind the next secret wall.

• Save before every new corridor. The demo's own how-to-play guidance nudges players to save often, per the creator's readthrough, and optional routes are exactly where an unprepared party dies.
• Carry food, not just potions. Resting restores health and consumes provisions, so a long optional detour is a supply problem before it is a combat problem.
• Cover two damage types. The creator's all-physical party immediately worried about oozes, which is the classic crawler trap: a magic source or a magic-damage weapon hedges it.
• Use one aura, level the rest. Demo tooltips state that only one aura can be active at a time and that leveling one aura raises the others, which makes swapping for a specific fight cheap. Player experience from the demo UI.
• Stock utility items. The demo shows locked doors you cannot open with the keys you hold, dig spots that need a tool, and burnt-out torches. Optional routes tend to hide behind exactly that kind of gate.
• Click everything and check the map. That combination of developer-confirmed hint policy and community habit is the cheapest way to find optional areas early.

Those habits remain useful even with a current player-written boss roster, because exact encounter order and optional status still need source-specific verification.

Underkeep Optional Bosses FAQ

Who are the Underkeep optional bosses? The official Steam store confirms optional bosses without naming a roster, while Steam's official achievements name the bandit chieftain and three High Clerics as encounter targets. A current player-written guide lists additional bosses and named foes — Rat Queen, Arachneira, Scourge of the Tunnels, Orc Chieftain, Dreadcoil of the Deep, Frog King, Obula, Skeleton King, Fangspire, Mud Ooze, and The Thing — but marks none of them as optional. Treat that list as reference only.

Is Skeleton King a boss in Underkeep? A current Steam Community player guide for app 2411200 lists Skeleton King under "Bosses and named foes." Treat that player-written classification as reference only, and verify the exact encounter role and location in the current build.

Is Gargant an Underkeep optional boss? No. Gargant belongs to The Underkeep, a four-player level 100 duty added to Final Fantasy XIV in patch 7.2, along with Soldier S0 and Valia Pira. Those fights have their own wiki and no connection to this game.

How do I find optional content while researching the boss list? Follow the developer's stated design: hidden buttons and passable walls exist, hints are placed, and secrets lead to optional areas or rewards without blocking the main story. Combine that with community habits — click every wall, watch the automap, and save before you commit.