All dungeons and towers each have their own unique final boss, which must be defeated in order to complete the level. Some may also contain mini-bosses, which are lesser bosses that usually appear in the middle of the dungeon instead of the end.
Bosses are different from normal mobs in that most of them possess the ability to deal special attacks, which deal more damage than basic attacks. Some special attacks are even able to instantly kill the player.
When defeated, bosses will glow light-blue instead of red before fading away. Bosses in towers will also grant the player chests.
In open worlds
Some bosses spawn during regular intervals in open worlds instead of dungeons. Unlike dungeons, players are not given a set amount of lives, so they cannot truly lose boss battles. However, the boss will disappear if the player(s) fail to defeat it in time.
World 1 (Crescent Cove)
- "Crabby Crusade" (1-1): Crabbage
- "Scarecrow Defense" (1-2): Blackened Raven
- "Dire Problem" (1-3): Dire Boarwolf
- "Kingslayer" (1-4): King Crab
- "Gravetower Dungeon" (1-5): Great Tree Ent, Elder of Jungle
World 2 (Embersky Jungle)
- "Temple of Ruin" (2-1): Goblin Gatekeeper (mini-boss), Goblin Knight (boss)
- "Mama Trauma" (2-2): Goblin Gatekeeper (mini-boss), Goblin Knight (mini-boss), Mama Quillodile (boss)
- "Volcano's Shadow" (2-3): Goblin Gatekeeper (mini-boss), Shadow of Cerberus (boss)
- "Volcano Dungeon" (2-4): Cerberus, Volcano Guardian
World 3 (Glacier Valley)
- "Mountain Pass" (3-1): Woolly Mammose
- "Winter Cavern" (3-2): Alpha Raptor, Beta Raptor
- "Winter Dungeon" (3-3): Castle Knights × 2 (mini-bosses), Winterfall, Ice Dragon (boss)
World 4 (Pharaoh's Canyon)
- "Scrap Canyon" (4-1): The Wasteland Tyrant
- "Deserted Burrowmine" (4-2): Buff Cactus (mini-boss), Sand Scorpion (boss)
- "Pyramid Dungeon" (4-3): Buff Cactus × 2 (mini-bosses), Anubis, Trickster of Titans (boss)
World 5 (Konoh Gardens)
World 6 (Atlantic Atoll)
World 7 (Mezuvia Skylands)
- The Underworld (7-1): Shadow of Cerberus (mini-boss), Hades, The Dark King (boss), Soul of Cerberus (boss)
- Hades' Maze: Sentry of Cerberus
World 8 (Wasteland Oasis)
- "Rescue in the Ruins" (8-1): Ruin Guardian (mini-boss), Ruin's Hand (boss)
- "Ruin Rush" (8-2): Roculus
- Christmas 2019-2021: Korrupted Klaus
- Halloween 2020-2021: Fallen King
- Twenty One Pilots 2021: Bishop
- Several bosses are taken from ancient mythologies and legends:
- Cerberus (boss of 2–4), in Greek mythology, is the faithful, three-headedd dog of Hades, whose job is to prevent the hellridden (in the Underworld) from leaving.
- Anubis (boss of 4–3), in Egyptian mythology, is the god of the afterlife.
- Davy Jones (boss of 6–1) is based on the idiom "Davy Jones' locker," meaning the bottom of the sea.
- The Siren (Atlantis Tower Floor 8), in Greek mythology, are hybrids between women and birds.
- Despite this, the boss lacks any bird-like characteristics in-game.
- The Kraken (Atlantis Tower Floor 10), in Scandinavian folklore, is an giant squid-like sea monster.
- Hades, The Dark King (boss of 7–1), in Greek mythology, is the god of the dead.
- Zeus (boss of Mezuvian Tower), in Greek mythology, is the god of the sky.
- The Minotaur (open world boss), in Greek mythology, is a monster depicted as being half-man, half-bull.
- The models of certain bosses have also been recycled, re-textured, and/or resized.
- Mama Quillodile is an enlarged Quillodile.
- The Shadow of Cerberus, Cerberus, Volcano Guardian, and Soul of Cerberus all use the same model.
- Great Tree Ent, Elder of Jungle, Root of Ignis, and Toa, Tree of the Ruins use the same model.
- Goblin Gatekeeper, Goblin Knight, Dark Goblin Knight Castle Knight, Castle Commander, Shield of Ignis, Ruin Guardian and Bishop use very similar models, with the only difference being their weapons.
- Great Poison Flower is an enlarged Poison Flower.
- Dragon Protector uses a similar model to Woolly Mammose, only without tusks.
- Fire Scorpion, Sand Scorpion, Whirlpool Scorpion, and Dark Scorpion use the same model.
- Buff Cactus and Buff Twins are both enlarged Happy Cacti.
- Elder Golem is an enlarged and re-textured Rock Golem.
- Big Blossom Tree and Corrupted Greater Tree are both enlarged Blossom Trees.
- Icy Blob is an enlarged Icy Goo.
- Eye of Ignis and Roculus appear very similar to Magma Goo.
- Mama Megalodile, Lava Shark and Gargantigator use the same model.
- Winterfall, Ice Dragon, Ignis, Fire Dragon, Ignah, The Son of Ignis, Ruinous, Poison Dragon and the dragon in the Twenty One Pilots event use the same model.
- Goblin Gatekeeper can spawn in three different colors.
- Anubis, Davy and Hand of Ignis use the same animations.
- Sand Scorpion has a new outlook in Oasis Tower.
- Taurha, Ruined Giant shares the same model with Fallen King's Second stage.
- Dire Boarwolf, Hades, The Dark King, Sentry of Cerberus and Ruin's Hand are bosses that appear both in dungeons and in open worlds.
- Crabbage, Castle Knight (World 3 event bosses only) and Ruin Guardian are the only two mobs that can be both a regular mob and a boss.
- Dire Boarwolf and Cerberus are only bosses that have a corresponding pet and mounts.
- Anubis, Trickster of Titans is the first boss that has a higher level than the dungeon's required level. This is due to the fact that Pyramid Dungeon originally had a higher required level.
- Before May 12th, 2022, Corrupted Greater Tree and Davy, King of the Sea were the only bosses that were not required for quests.
- The bosses of all world final dungeons, as well as all the final bosses of towers, provide badges to the player when defeated.
- Bishop is the only Event Boss that awards the player with an avatar accessory.
- In volume, the Kraken is the largest boss and the Crabbage is the smallest.
- The Kraken is the only boss that is completely immune to player attacks. Instead, players must attack its tentacles instead of its body.
- Winterfall, Corrupted Greater Tree, Ignis, Davy, the Kraken, Taurha and Fallen King are the only dungeon bosses that have an instant-kill ability.
- Ranged Classes is considered the most effective class for fighting bosses as many bosses are not capable of ranged attacks. And it can also move while attacking.
- Some boss battles recycle soundtracks from other bosses or dungeons.
- The Crabbage's battle uses the soundtrack for Rough Waters (dungeon 6-1).
- Mama Quillodile and the Shadow of Cerberus have the same battle soundtrack.
- Corrupted Greater Tree and Davy, King of the Sea have the same battle soundtrack.
- In its first stage, Zeus, Lord of the Sky uses a soundtrack from Winter Cavern (dungeon 3-2).
- In its second stage, the boss uses the same soundtrack as the mini bosses in the Atlantis Tower.
- Korrupted Klaus uses the soundtrack from Winter Dungeon (dungeon 3-4).
- The Ruin's Hand and Roculus uses the soundtrack from the Fallen King's first stage.
- Taurha, Ruined Giant uses the soundtrack from Konoh Heartlands (Dungeon 5-1).
- World Bosses in World 8 uses the same sound track from Oasis Tower's wave defense stage.