These are the AU's that the author has invented, most of them are not by the author and do not belong. The ones is capitals are the ones it owns. Each one has a Chadley in it, too. Which the author can transform into something new.

UNDERTALE: ORIGINS (A whole different story but maybe something like before Undertale)

Aftertale (After Frisk leaves genocide route)

Beforetale (Before frisk fell)

ERRORTALE (A timeline where everything is decayed and Error Sans is never alone again)

Underfresh (Everything is swaggy fresh and funky (lmao))

Outertale (Somewhere in space there is a land in an asteroid)

SUICITALE (Where everything doesn't have a purpose, hope, or dreams anymore)

Underswap (Where everything is swapped and switched around)

Underfell (Where everything is violently vile and have no mercy for the innocent)

Gastertale (I think everyone is fused with W.D. Gaster)

HUMANTALE (Where monster switched to human)

NEKOTALE (Everyone is a neko)

Mafiatale (I thiiiiiiiiiink a rebel group)

BLOOKTALE (Everyone is a ghost like Napstablook)

FLOWEYTALE (Everyone has turned into a flower)

GENDERTALE (Everyone's gender's are switched)

Reapertale (Where reapers and goddesses roam the Earth, taking souls or guidance)

WAIFUTALE (Where everyone is in a dress or some wedding thing)

YANDERETALE (Everyone has a lust to destroy for their beloved crush known as Senpai)

Zephyrtale (Where fantasy and monsters come to life, like a warriors and warlocks)

UNDERTUBE (Where everyone is a YouTuber and has that personality)

UNDERLOID (Where Vocaloid songs come from their life to songs)

LITERALTALE (Literally life)

MY LITTLE TALE (Everyone is a pony)

FIVE NIGHT'S AT UNDERTALE (Everyone is a animatronic and nightguard trying to survive)

THE LEGEND OF UNDERTALE (The Legend of Zelda but different people)

MAIDTALE (Where in water, mermaids and deep creatures roam a far away land)