Shadow

The Shadow is a Pureblood Heartless that is found in all Kingdom Hearts games except Kingdom Hearts Birth by Sleep because it precedes the creation of the Heartless. Although the Shadow is not the absolute weakest type of Heartless, it is the most basic type, and is still a threat to those without the Keyblade. It is found in each world in every game, excluding Atlantica in Kingdom Hearts and Kingdom Hearts: Chain of Memories. Certain Heartless, such as the Darkside, the Dark Follower, or Xehanort's Heartless, can also summon Shadows, and the Shadows spawned by the Dark Follower are in fact violet, rather than the traditional black.

Kingdom Hearts
''Heartless that emerge from various places. They sneak up to their enemies and strike them with sharp claws. They are extremely tenacious, often chasing their prey to the end.''

Kingdom Hearts: Chain of Memories
A Heartless that pops up in all kinds of places.

''The Shadow ambles around and attacks without warning. It is completely untouchable while hiding within the darkness.''

Kingdom Hearts II
It sinks into the ground while moving, so timing is the key to defeating it.

The moment it surfaces, attack away!

Kingdom Hearts 358/2 Days
A Pureblood Heartless that flows across the ground as a shadow, completely immune to attack.

Watch for the moment it emerges, then strike!

Kingdom Hearts
The Shadows first appear within Sora's Awakening, but are summarily destroyed by Sora, along with the Darkside, and he awakes from his dream. However, when Riku opens the door to Destiny Islands' heart, the Shadows reappear to devour the children's island. Sora notices the storm caused by their arrival and races to the island, but although he attacks them with his Wooden Sword, he is unable to damage the eldritch monsters until he discovers the Keyblade. Although he is now equipped to fight back the horde, his friends have already fallen into the darkness, and the island's heart has been devoured.

Shadows continue to appear as minor Heartless throughout the worlds, but do not reappear in force until Sora completes the Door to Darkness at Hollow Bastion by releasing Kairi's heart from his body. Not only does this change him into a Shadow Heartless, but the triumphant Ansem summons a swarm of Shadows to chase Kairi, Donald, and Goofy from the castle. However, at the Entrance Hall, Kairi notices the Shadow that is Sora and embraces him, giving him back his human form.

Kingdom Hearts 358/2 Days
Shadows appear in the Mission Mode tutorial when the player learns about collecting Mission Points. They also appear when Roxas trains with Marluxia, Marluxia then proceeding to tell Roxas why the Organization ignored Pureblood Heartless, using the Shadow as an example. Much later in the storyline when Roxas went to Halloween Town on a mission in which he was to meet up with Xigbar, he was surrounded by Shadows before being rescued by the latter.

Kingdom Hearts: Chain of Memories
Several Shadows spawned when Sora and company attempted to leave the card world of Monstro, as well as when Jack Skellington mentioned a "problem" in Halloween Town.

Kingdom Hearts II
When Sora, Donald, and Goofy, as well as Kairi and Riku separately enter the Hall of Empty Melodies, a swarm of Shadows appears and attacks them. Riku lends Kairi a Keyblade, and they each fight back the swarm. However, it is Xigbar who finishes the Heartless off, before he challenges Sora to battle. After Ansem fires the Kingdom Hearts Encoder at Xemnas's artificial Kingdom Hearts, the shower of hearts that results attracts a gigantic swarm of Shadows, who attack the castle. Maleficent and Pete offer to hold off the Shadows so that Sora and his friends can defeat Xemnas, in exchange for the castle itself. When the castle is destroyed in Xemnas's final assault, it is assumed that the Shadows are as well.

Abilities
Shadows live up to their name, emerging from the ground to attack with a simple but fierce claw strike. Although the Shadow is relatively easy to defeat when alone, its habit of attacking in swarms can make it too much to handle.

Kingdom Hearts

 * Awakening
 * Destiny Islands
 * Traverse Town
 * Wonderland
 * Deep Jungle
 * Olympus Coliseum
 * Agrabah
 * Monstro
 * Halloween Town
 * Neverland
 * Hollow Bastion
 * End of the World

Kingdom Hearts: Chain of Memories

 * Traverse Town
 * Wonderland
 * Olympus Coliseum
 * Agrabah
 * Halloween Town
 * Monstro
 * Neverland
 * Hollow Bastion
 * Twilight Town
 * Destiny Islands
 * Castle Oblivion
 * Bottomless Darkness

Kingdom Hearts II

 * Twilight Town
 * Hollow Bastion/Radiant Garden
 * The Land of Dragons
 * Beast's Castle
 * Underworld
 * Disney Castle
 * Timeless River
 * Port Royal
 * Agrabah
 * Halloween Town
 * Pride Lands
 * The World That Never Was

Kingdom Hearts 358/2 Days

 * Twilight Town
 * Wonderland
 * Olympus Coliseum
 * Agrabah
 * Beast's Castle
 * Halloween Town
 * Neverland

Strategy
It is best to fight alone being quite weak, but it mostly shows up in groups, making it harder to fight. If it is too much, it is a good idea to use lightning (only in Kingdom Hearts) because it has a wide range. If it is alone, just fight it with the keyblade.

Kingdom Hearts

 * Claw Attack

Kingdom Hearts: Chain of Memories

 * Claw Attack
 * Slide Kick

Kingdom Hearts II

 * Left Claw
 * Right Claw
 * Pounce Claw