Human

Humans were a race that lived on the surface of the Earth, beyond the barrier on Mount Ebott.

Overview
Humans had once ruled over Earth alongside monsters, but a war had soon broken out between both species. During the war, an unidentified human wielding a sword appeared to be leading their species, who were carrying weapons such as spears and torches, into battle, as seen in Frisk's visions. After humans claimed their victory, they gathered behind their leader and witnessed as a mage, using a magical spell, sealed the monsters underground.

Humans had lived on the surface ever since they won the war. Eight humans were known to have fallen into the Underground: the First Human, Frisk, and the six humans whose SOULs were stored in New Home. Humans as a whole were seen as evil by monsters, especially since Asgore declared to kill any human who entered the Underground, yet most monsters did not know what a human looked like. The job of patrolling for humans was entrusted to the Royal Guard.

Humans indirectly affected the monsters' society. Waste from human society flowed through rivers into the Garbage Dump. This waste had influenced monsters' technology and media; for example, anime and manga remained one curiosity to monsters. This waste had also distorted monsters' perception of human society, such as Undyne believing anime to be human history. Acculturation of human customs occurred as well, such as Mettaton's interest of keeping his resort's standards similar to those of humans.

Physiology
Human bodies were composed of physical matter, as opposed to monsters' more magical bodies. Because of this, human SOULs were not attuned to their bodies like monsters were. This trait allowed their SOULs to persist after death. The physicality of human bodies also allowed humans to carry higher concentrations of determination than a monster.

It appeared that humans were once capable of magic, as seven mages used a magical spell to seal monsters underground.