Shadow the Hedgehog is a character that appears in the Sonic the Hedgehog series. He is an anthropomorphic hedgehog/Black Arms hybrid who resembles Sonic the Hedgehog in many ways and serves as his arch-rival and occasional ally. Shadow was created as the "Ultimate Life Form" by Gerald Robotnik by using the DNA of Black Doom and is the final result of Project Shadow. His purpose was to provide ways to develop a cure for incurable deadly illnesses, more specifically for Gerald's granddaughter.