Shadow the Hedgehog is a hedgehog infused with Black Arms' DNA. He was created as the "Ultimate Life Form" by Dr. Gerald Robotnik. He was created to be the cure to incurable diseases, but more specifcally for Gerald's granddaughter Maria Robotnik. Unfortunately, early after his birth he was captured by G.U.N. and put into stasis.

50 years later, Shadow was released by Gerald's grandson, Dr. Eggman. Shadow originally worked alongside the doctor, but he secretly wanted to destroy Earth as revenge for the murder of Maria. Shadow has lost his memories from the stasis and slowly uncovered his past. After the events of Shadow the Hedgehog (2005), he regains his memories and continues to now be an anti-hero while also seeking revenge for Maria.

Shadow is an edgy, sharp-witted hedgehog. He always has a strong sense of purpose and like to accomplish his goals with any means necessary. Shadow can math the speed and skills of Sonic the Hedgehog, but also has the power of Chaos Control, the ability to harness the power of an Chaos Emerald to warp through time and space.