Leitmotifs

A leitmotif (/ˌlaɪtmoʊˈtiːf/) is a musical "phrase" or melody, re-used in multiple songs to associate a tune with a person, event, or place.

The extensive use of leitmotifs in Undertale 's soundtrack and other sound files helps create a nostalgic mood for the game and often evokes emotional responses in players. Toby Fox has stated that the majority of Undertale 's soundtrack was composed using reiterations of free SoundFonts and synths.

Attempts have been made at documenting all of the leitmotifs used in the game ; players frequently find new connections, and it may be impossible to list them all conclusively. Every single data can be considered interpretations and every single change must be explained in history description.

Timestamps found below are approximate to one second and are sourced from this playlist, which reflects the timing of the official soundtrack.

Once Upon a Time


This leitmotif can be considered as the theme of Undertale. It's the most common melody of the game, playing in seventeen tracks.
 * Once Upon a Time
 * Start Menu and Menu (Full) (the background tracks for the Start Menu build upon one another, with five intermediate tracks in between and the music played in the menu at the end of a True Pacifist playthrough is a slowed rendition of Start Menu)
 * Home and Home (Music Box) 0:36-1:44
 * Hotel 0:20-1:22
 * Can You Really Call This A Hotel, I Didn't Receive A Mint On My Pillow Or Anything 0:14-0:57
 * Undertale 0:37-5:58
 * The Choice
 * Fallen Down (Reprise) 1:18-2:30 syncopated to 3/4
 * Hopes and Dreams 0:00-1:29, 1:52-2:14
 * SAVE the World 0:35-1:46
 * Final Power (reversed)
 * Reunited 0:43-3:56
 * Bring It In, Guys! 3:47-4:05
 * Last Goodbye 0:00-0:25, 0:45-2:15
 * Good Night

Flowey


This leitmotif occurs in six songs, and one unused audio file.
 * Your Best Friend
 * Premonition
 * Your Best Nightmare 0:54-1:26, 2:00-2:27, 3:00-3:27
 * Finale 0:00-0:40, 0:57-1:52
 * Hopes and Dreams 1:29-1:52
 * SAVE the World 1:35-1:46
 * mus_toomuch (this plays after exhausting the random kill counter of an area)
 * mus_f_finale_1

Toriel

 * Fallen Down (the track in-game is played 25 cents above C# major in A440 equal-tempered tuning ; the sheet music shown above is written in D major)
 * Fallen Down (Reprise) 0:00-1:18
 * Bring It In, Guys! 3:34-3:47 syncopated to 4/4
 * Empty House

Ruins


This leitmotif can be considered as the underground theme, appearing in thirteen official songs and an unused sound file.
 * Ruins
 * Waterfall 0:27-1:56
 * Quiet Water
 * NGAHHH!! 0:34-1:22
 * Spear of Justice 0:36-1:55
 * An Ending
 * Don't Give Up
 * SAVE the World 0:00-0:35 syncopated to 4/4
 * Respite
 * Bring It In, Guys! 1:48-2:14
 * Last Goodbye 0:25-0:45 syncopated to 4/4
 * Battle Against a True Hero 0:00-1:36 and Power of "NEO"
 * mus_ruinspiano

Enemy Approaching

 * Anticipation (this song also plays at extremely reduced speeds when battling Monster Kid, during the final encounters with Flowey in New Home, and at the end of a "Soulless" Pacifist playthrough)
 * Enemy Approaching
 * Heartache (specific ariation)
 * Dogsong, has the variation of the melody (a slowed version of this song plays after meeting Endogeny's sparing conditions)
 * Temmie Village, also has the variation
 * Tem Shop, also has the variation
 * Stronger Monsters
 * ASGORE 0:34-1:49 (Heartache variation)
 * Bring It In, Guys! 0:00-0:34
 * Dogtroid

Ghost Fight

 * Ghost Fight
 * Dogbass (bassline)
 * Dummy!
 * Pathetic House
 * Spider Dance

Determination

 * Determination
 * This song is sped up, looped, and played over itself, as Flowey laughs at the protagonist for dying to him.
 * ASGORE 1:50-2:28 syncopated to 4/4
 * mus_snoresymphony
 * mus_kingdescription

Sans


Found in four songs, one of which is never played in the game.
 * sans.
 * It's Raining Somewhere Else (this song is played slightly slower in Sans's Room)
 * Song That Might Play When You Fight Sans
 * Bring It In, Guys! 0:40-0:46

Papyrus

 * Nyeh Heh Heh!
 * Bonetrousle (this song is played at an extremely reduced speed when encountering Papyrus for the last time in the Genocide Route )
 * Song That Might Play When You Fight Sans 0:33-0:58
 * Bring It In, Guys! 0:34-0:53

Hopes

 * Snowy 0:00-1:03 (this song plays when fighting Snowdrake's Mother. It is heavily distorted, changing pitch and speed randomly every few seconds)
 * Snowdin Town 0:00-0:56
 * Shop 0:00-0:25
 * Dating Start! 0:00-0:16, 0:37-0:54, 1:31-1:56
 * Dating Tense!
 * Dating Fight! 0:00-0:13
 * Hopes and Dreams 0:44-1:07
 * Reunited 0:00-1:43
 * Bring It In, Guys! 0:54-1:16

Dreams
Partition needed.
 * Snowy 1:03-1:42, syncopated
 * Snowdin Town 0:56-1:16
 * Shop 0:25-0:50
 * Dating Start! 0:16-0:35, 0:54-1:31
 * Dating Fight! 0:13-0:35
 * Confession
 * Hopes and Dreams 2:15-3:01
 * Reunited 3:56-4:25
 * Bring It In, Guys! 1:16-1:29

Undyne

 * Undyne
 * Run! syncopated to 4/4
 * Dating Tense! 0:17-0:25 syncopated to 4/4
 * NGAHHH!! 0:00-0:34, has the variation of the melody
 * Spear of Justice 0:00-0:36, also has the variation
 * ASGORE 2:28-2:36, syncopated to 4/4
 * Bring It In, Guys! 1:29-1:48, also has the variation

Waterfall


The theme originates from the song "Doctor" from Homestuck.
 * Waterfall 0:00-0:27, 1:56-2:07
 * Another Medium, has four variations of the melody.
 * CORE, also has variations.
 * Death by Glamour, also has variations.
 * Bring It In, Guys! also has variations.
 * mus_star (debatable)

Alphys

 * Alphys
 * Bird That Carries You Over A Disproportionately Small Gap
 * She's Playing Piano
 * Here We Are
 * But the Earth Refused to Die
 * Battle Against a True Hero 1:36-2:36

It's Showtime!


Found in ten songs and at least one other sound file.
 * It's Showtime!
 * Metal Crusher 0:04-0:19, 0:37-0:53
 * Hotel, has the variation of the melody
 * Can You Really Call This a Hotel..., also has the variation
 * Live Report syncopated to 3/4
 * Death Report syncopated to 3/4
 * CORE Approach syncopated
 * Oh My..., also has the variation
 * Death by Glamour 0:12-0:25, 0:35-1:04 (variation), 1:30-1:56
 * Bring It In, Guys! 2:21-2:33, also has the variation
 * mus_tv (i.e., Papyrus's TV)

Metal Crusher


This leitmotif originates from Noisemaster's Theme from Cucumber Quest.
 * Metal Crusher 0:20-0:37
 * Last Episode!
 * Death by Glamour 1:04-1:30

Asgore

 * Bergentrückung
 * ASGORE 0:00-0:33
 * Bring It In, Guys! 3:25-3:34

You Idiot

 * You Idiot
 * Your Best Nightmare 0:00-0:16, 0:22-0:53, 1:27-1:54, 2:29-2:54, 3:28-4:00
 * Burn in Despair!
 * mus_f_part3

Asriel

 * Memory
 * Undertale 0:00-2:47, 3:27-6:21 (at times, the melody is barely perceptible among overlapping music. It is heard on a guitar for most of the song, becoming hard to distinguish after 3:27. The tune switches to a more audible sample after 4:42, to a quiet background piano at the key change around 5:20, and back to the second SoundFont at 5:57)
 * The Choice (imperceptible), as it is a part of Undertale which contains the barely-audible Memory
 * Finale 0:40-0:57
 * His Theme

Minor Leitmotifs

 * The Joystick Config songs - Uwa!! So Temperate♫, ...Holiday♫, and ...HEATS!!♫ - are all variations of each other.
 * Home to Home (Music Box)
 * Dating Start! to Dating Fight!
 * Spooktune to Spookwave
 * Ghouliday to Jingle Bells
 * Hotel to Can You Really Call This a Hotel...
 * Live Report to Death Report
 * Oh! One True Love to Oh! Dungeon and For The Fans
 * Battle Against a True Hero 0:00-1:36 to Power of "NEO"
 * MEGALOVANIA to its previous incarnations.
 * Gaster's Theme has debatable uses in some songs.

Similar samples

 * Sample used in Barrier is used in Amalgam
 * Sample used in Ooo is used in Waterfall (0:14-0:25)
 * Flowey's Laugh is used in Your Best Nightmare (0:16-0:22)
 * mus_smile is Muffet's laugh, sped up, reversed, and looped.
 * Multiple songs from the soundtrack use instrument samples from other games.