Sonic the Werehog (also known as Werehog Sonic, Beast Sonic or simply the Werehog) is a corrupt transformation that Sonic the Hedgehog undergoes in Sonic Unleashed. It is caused by Dr. Eggman and a special ray that hits Sonic with Dark Gaia's power, in turn, the energy from Dark Gaia had turned Sonic into this from. Sonic finds out at sundown he changes into the Werehog. When Dark Gaia awakened, he tried to destroy Chip but Sonic managed to push him out of the way. Dark Gaia, outraged, took Sonic's Dark powers away from him.
- Super Stretch: Sonic has the ability to stretch his arms which is useful to grapple on poles and higher ledges.
- Super Strength: This allows Sonic to lift sealed doors and heavy metallic objects.
- Speed Fighting:Whenever Sonic fights, he shows to have unbelievable Speed in fighting, it is possible that whenever he turns into the Werehog, all the speed he has in his legs go into his arms.
- Invincibility:Just like Super Sonic, the Werehog can turn Invincible and can't be damage by other attacks, however, this ability can only last for a short time.
- Unleash: From defeating multiple enemies, Sonic has the option to activate Unleashed mode. This is caused by more Dark Gaia energy from the enemies that Sonic defeats and he uses it to make him self amazingly stronger, power-up combos and on the PS3/360, become invincible. However, this only lasts a short period of time.
- Sonic's gloves were torn apart during his first transfromation into the Werehog. Because of this, Sonic the Werehog is is one of the few non-robitic characters to not wear gloves. Oddly, when he turns back into his normal form, his gloves magically repair themselves.In the Xbox 360/PS3 version of Sonic Unleashed, Chip will even acknowledge this if the player feeds him enough by asking, "Where do you put your gloves at night?"
- The term "Werehog" is derived from the words, "Werewolf" and "Hedgehog." However, this is a misnomer, condidering that the the "Were" in "Werewolf" derives from the Old English "Wer", meaning "Man" which means that he is incorrectly referred to as "Manhog".