|Signs of nearing||Spawning|
|Theme song||Night of Fate|
The Heartless are the group of bosses that appeared on Slender Fortress.
Pureblood Heartless are natural Heartless, born from the darkness in people's hearts. They are ink-black in color, with yellow beady eyes. They are more common in places that are close to or saturated in darkness. Upon their destruction, they simply disappear in puffs of darkness, 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. Afterward, stolen hearts can become Emblems. They have more varied shapes, colors, and are branded with Xehanort's symbol to differentiate them from the Pureblood ones. They are more common on the worlds within the Realm of Light, and usually mimic the shape of creatures or objects within that world.
Heartless, Emblem or Pureblood, possess several key characteristics that define them as Heartless. Most Heartless are created when the darkness that resides in a person's heart consumes him or her, thus giving the darkness shape and form; this process will occasionally also form Nobodies, which are born from the body and soul left behind when the heart is lost. Being born from darkness, they are mindless and act on instinct, their only goal is to find hearts, and consume them to create more Heartless. But what they desire above all are the hearts of worlds, and thus they enter worlds in search of the way into the hearts of the worlds. When they consume these colossal hearts, the remains of the world form new worlds, such as Traverse Town and the End of the World.
At the same time, Heartless seek out the users of the Keyblade, since the Keyblade holds the power to lock and unlock hearts. In order to stop the users of the Keyblades, the Heartless use the Keyblade itself as a homing beacon, but ultimately desire to take the heart that commands it. Because of this, Keyblade wielders are under constant attack.
The strength of a Heartless is proportional to the depth of the darkness from which it was born. The darker the heart forming a Heartless, Emblem or Pureblood, the more powerful and more monstrous the resulting being will be. An exception to this is Xehanort's Heartless, who retained his human appearance for unknown reasons. This is a contrast to Nobodies, which determine rank according to the strength of the heart, and whose appearances become more human as they increase in power. Furthermore, as beings of elemental darkness, the Heartless are able to take possession of other beings or even inanimate objects, granting them immense dark power and often reshaping their very forms to suit their purpose.
The Heartless, being mindless, usually have no master to direct their actions and instead act on the instinct to gather more hearts. However, there are some higher beings who can command them. Heartless will obey those with an affinity for darkness and a strong will. If many people attempt to control them, the Heartless will side with whomever is most powerful. Those with hearts, such as Maleficent, endanger themselves however, as the Heartless are attracted to their hearts and if they show weakness, the Heartless will not think twice of consuming their hearts.
On the other hand, higher ranking Heartless, like Xehanort's Heartless, can fully command other Heartless without endangering themselves. Also, Organization XIII is able to command them as well with their strong wills, but are not endangered of being consumed by them for their lack of a heart. Heartless make use of the "corridors of darkness", inter-dimensional pathways that connect the many worlds. These pathways are located in the Realm of Darkness, and thus are very dangerous to use if one is not accustomed to the darkness.
A normal Shadow has a vaguely humanoid body structure. It has a round, spherical head with circular, glowing yellow eyes. It also has two long, twisted antennae sprouting out of the top of its head. Each of its hands has three clawed fingers, and its feet are large and lack any discernible digits. With the exception of its eyes, this Heartless's body is completely black (with the exception of the Shadows summoned by the Dark Follower, which are dark purple).
The Shadow's name is a reference to a shadow, highlighting its status as the most basic type of Heartless. The name could also be a reference to the Shadow's ability to flatten itself into a silhouette on the ground, and become a literal shadow.
In Slender FortressEdit
Shadows emerge from the ground to attack with a simple but powerful scratch attack. These Heartless are easy to defeat on their own, but their habit of attacking in large swarms can be quite overwhelming. They do minimal damage but they will attack you quickly. To make them go away, melee them.