Boss

Bosses and minibosses in Undertale are unique enemies that can only be encountered once. They are often mandatory encounters that must be defeated to progress the story. They can use more advanced attack patterns that are of a higher difficulty than standard monster encounters, and they are often capable of moving or altering the bullet board.

Defeating bosses and minibosses a certain way can influence the ending the protagonist achieves at the end of the game.

List of bosses

Note: These bosses are listed in order of their first appearance. Clicking on the character's image leads to their "In battle" section or subpage, while the listed name underneath leads to their main article.

Ruins

These bosses appear in the Ruins.

Boss	Type	Track	Map link
Napstablook	Miniboss	Ghost Fight	Map link
Toriel	Boss	Heartache	Map link

Snowdin

These bosses appear in Snowdin and Snowdin Town.

Boss	Type	Track	Map link
Doggo	Miniboss	Enemy Approaching^{[note 1]}	Map link
Lesser Dog	Miniboss	Enemy Approaching^{[note 1]}	N/A^{[note 2]}
Dogamy and Dogaressa	Miniboss	Enemy Approaching^{[note 1]}	Map link
Glyde	Miniboss^{[note 3]}	Enemy Approaching^{[note 1]}	Map link
Greater Dog	Miniboss	Dogsong	Map link
Papyrus	Boss	Nyeh Heh Heh! Bonetrousle	Map link
Mad Mew Mew	Miniboss^{[note 3]}^{[note 4]}	Mad Mew Mew	Map link

Waterfall

These bosses appear in Waterfall.

Boss	Type	Track	Map link
Shyren	Miniboss	Enemy Approaching^{[note 1]}	Map link
Mad Dummy	Miniboss^{[note 5]}	Dummy!	Map link
Glad Dummy	Miniboss^{[note 6]}	Anticipation	Map link
Undyne	Boss^{[note 5]}	Spear of Justice	Map link
Undyne the Undying	Boss^{[note 6]}	Battle Against a True Hero	Map link

Hotland

These bosses appear in Hotland and the CORE.

Boss	Type	Track	Map link
Royal Guards	Miniboss	Enemy Approaching^{[note 1]} Confession	Map link (Neutral Route) Map link (Genocide Route)
So Sorry	Miniboss^{[note 3]}^{[note 5]}	Wrong Enemy !?	Map link
Muffet	Miniboss	Spider Dance	Map link
Mettaton EX	Boss^{[note 5]}	Death by Glamour	Map link
Mettaton NEO	Boss^{[note 6]}	Power of "NEO"	Map link

True Lab

These bosses appear in the True Lab.^{[note 7]}

Boss	Type	Track	Map link
Memoryhead	Miniboss	Amalgam	Map link
Endogeny	Miniboss	`mus_woofenstein_loop` Dogsong	Map link
Reaper Bird	Miniboss	Amalgam	Map link
Lemon Bread	Miniboss	Amalgam	Map link
Snowdrake's mother	Miniboss	Snowy	Map link

New Home

These bosses appear in New Home.

Boss	Type	Track	Map link
Asgore	Boss^{[note 5]}	ASGORE	Map link
Omega Flowey	Final boss^{[note 5]}	Your Best Nightmare Finale	Map link
Asriel	Final boss^{[note 7]}	Hopes and Dreams Burn in Despair! SAVE the World His Theme	Map link
Sans	Final boss^{[note 6]}	MEGALOVANIA	Map link

Outside of Undertale

This boss occurs outside of Undertale.

Boss	Track	Link
Sans (10th Anniversary Stream)	Song that Plays when Somebody Verses sans.	undertale.com

Notes

1 2 3 4 5 6 Default general battle music
↑ This encounter occurs randomly.
1 2 3 This encounter is optional.
↑ Exclusive to the Nintendo Switch version
1 2 3 4 5 6 Only on Neutral Route
1 2 3 4 Only on Genocide Route
1 2 Only on True Pacifist Route

[default_music-1] 1 2 3 4 5 6 Default general battle music

[2] This encounter occurs randomly.

[optional-3] 1 2 3 This encounter is optional.

[4] Exclusive to the Nintendo Switch version

[neutral-5] 1 2 3 4 5 6 Only on Neutral Route

[genocide-6] 1 2 3 4 Only on Genocide Route

[pacifist-7] 1 2 Only on True Pacifist Route

[note 1]

[note 2]

[note 3]

[note 4]

[note 5]

[note 6]

[note 7]