人怪戰爭（The War of Humans and Monsters）是一場Undertale故事發生前的史詩級戰爭。
- "* Not a single SOUL was taken, and countless monsters were turned to dust...'" - Ancient Glyphs in Waterfall</ref>。最後，怪物們投降了，而人類迎來了勝利。人類聚集了他們當中最強的七位魔法師，並且用法術將怪物封印在伊波特山的下面。
- ↑ ""A monster with a human SOUL...
- A horrible beast with unfathomable power.
- The humans, afraid of our power, declared war on us.
- They attacked suddenly, and without mercy." - Ancient Glyphs in Waterfall * " - Ancient Glyphs in Waterfall
- ↑ ""* Humans are unbelievably strong.
- It would take the SOUL of nearly every monster...
- ... just to equal the power of a single human SOUL."- Ancient Glyphs in Waterfall"- Ancient Glyphs in Waterfall
- ↑ ""* Seven of their greatest magicians sealed us underground with a magic spell." - Ancient Glyphs in Waterfall
- ↑ "* Trapped behind the barrier and fearful of further human attacks, we retreated. *, far into the earth we walked, until we reached the cavern's end. * This was our new home, which we named... * "Home."" - Book at Toriel's Home
- ↑ "* Fearing the humans no longer, we moved out of our old city, HOME. * We braved harsh cold, damp swampland, and searing heat... * Until we reached what we now call our capital. * "NEW HOME."" - Book at Asgore's Home