The Heartless are dark beings from the Kingdom Hearts series, born when a person loses his/her heart to darkness. The Heartless are the primary enemy types in the Kingdom Hearts series, with various subspecies appearing as enemies in almost every game. While most Heartless are in fact manifested hearts, they behave entirely devoid of emotion, and thus are named "Heartless".

The Heartless come in two forms: "Pureblood" and "Emblem". Pureblood Heartless are natural Heartless, born from the darkness in people's hearts. They are ink black in color, have yellow beady eyes, and, upon their destruction, they simply disappear in puffs of black smoke, without a heart leaving its body.

Emblem Heartless, on the other hand, were originally created from machines that reproduce the process of a heart being consumed by darkness, and thus have more varied shapes, colors, and attributes. Emblem Heartless are branded with a distinct red and black heart insignia in order to differentiate them from their Pureblood counterparts.

See also: Nobody