Darkside

Darkside is a boss from Kingdom Hearts.

Darkside was a colossal pure Heartless that Sora encountered numerous times. Instances included in the mysterious Station of Awakening, the Destiny Islands, and in the End of the World (though this may have taken place in the Destiny Islands as well). The name may originate from the narrator's dialogue during Sora's first clash against the titan, which tells of darkness coming to the heart.

Darkside can spawn Shadows.

Twilight Thorns are very similar to Darkside. It is possible that they are related.