Nazo

Nazo refers to a mysterious blue-gray glowing hedgehog-like creature that has only appeared in an early pilot for Sonic X.

Overview
In the pilot, Nazo appears only in one shot for couple of seconds. The image of him also appeared on Sega's official Japanese website and was entitled "Nazo.jpg", which has led to some fans assuming that Nazo was to be this character's name. This is however questionable because the word "Nazo" means "mystery" in Japanese, leading others to believe "Nazo" was only used as a file image as a placeholder for the actual name.

The character did not appear in the anime and no information has been given about him; so much debate has followed about who he was to be. Many assume that he was to be a villain, or Hyper Sonic, but there is nothing to support these but one's interpretation of the image. Nazo bears little resemblance to any of the characters and has spikes that branch from both sides of his back.