Dark Hide

The Unnamed Heartless is a minor villain in the video game; Kingdom Hearts Birth by Sleep. It's a Pureblood Heartless that attacks Aqua when she was in the Realm of Darkness.

History
While making her way through the Valley of the Darkness in an attempt to return home, Aqua is being stalked by a strange creature with bloodshot red eyes. Upon moving in the shadows, Aqua notices the Heartless's presence, and draws the Masrter Keeper. The Heartless emeges from the shadows and attacks Aqua from behind, knocking her down. Aqua quickly retaliates with a Fire spell, forcing it to back off to the shadows, showing Aqua nothing but its red eyes.

Almost instanily, Aqua realized that the creature was not an Unversed, and like the other creatures she's been facing. Instead, it was another creature that she encountered while she was in the Realm of Darkness. She then processed to engage the Heartless in a one-on-one battle. After a long and strenuous showdown, Aqua emerged victorious. However, the fate of this nameless creature is currently still unknown.