Dark Shadow is a transformed state of Shadow the Hedgehog that appears in Shadow the Hedgehog. It is the opposite of Hero Shadow, achieved when Shadow's mind is fueled by thoughts of vengeance, and once obtained, grants him full control over negative chaos energy.
When utilizing Dark Shadow, Shadow does not change much physically. However, his fur and his eyes get a neon red coating of negative chaos energy and he gains an explosion-like neon red aura.
While in this form, Shadow becomes invincible and can use Chaos Blast, a destructive discharge that wipes out everything within a 20-yard range, for a limited amount of time, as well as use any weapon without draining its ammo/durability. In most cases, Dark Shadow can be obtained by filling Shadow's Dark Gauge. The only other instance this form can be obtained is when fighting the Egg Dealer and causing the Egg Dealer to use Shadow Fever. This form can also be used in Shadow's Super State.
Dark Shadow appears in the game's intro, where he is being pelted with bullets by four GUN Soldiers in vain. He emerges from the fog and debris and uses the Chaos Blast to blow them all away.
- Dark Shadow appears in an unused CGI TV spot for Shadow the Hedgehog. Shadow is seen approaching the camera as a silhouette from the thick cloud of fog. As his body begins to glow red, an explosion triggered by thunder occurs behind him and rushes at him.
- It should be noted that Dark Shadow is a different ability compared to Chaos Boost; however, the two bestow Shadow with similar abilities, suggesting the two may be related.