Project Shadow (Sonic X)

Project Shadow was a scientific project in the Sonic X anime.

Overview
Project Shadow was a medical research funded by the government in hopes of learning how to obtain immortality. The results of the project produced Shadow the Hedgehog, the final product, and the Biolizard, a prototype, both of whom had managed to gain immortality.

Soon after the completion of these two creatures, the project was shut down by GUN, as it was considered too dangerous to humanity. This shit down led to the deaths of Gerald and Maria Robotnik. The Biolizard was then sealed away aboard the ARK while Shadow was sent down to Earth in a capsule.

Trivia

 * Sonic and Shadow's similarities in appearance are never explained, which becomes even more confusing when one realizes that Shadow was technically created in another universe altogether.
 * This also begs the question of how Gerald even knew of the existence of the Chaos Emeralds.