Evil Ash, officially known as Ash crazed by the Spiral of Blood (血の螺旋に狂うアッシュ Chi no Rasen ni Kuruu Asshu), is the final boss in The King of Fighters XIII. He was initially referred to by fans as Dark Ash and is the fusion of Ash Crimson and Saiki. His appearance is essentially Ash wearing black clothing and with white hair. He is unplayable in both arcade and home versions, but the secret character Saiki can be considered a balanced, playable form of Evil Ash in the home versions. He is voiced by Sōnosuke Nagashiro.
After Saiki fought the winners, Ash attacks him from behind and absorbs his energy. This backfires as Saiki's influence takes over during the process and as a result the two fuse into a single entity.
Evil Ash battles the tournament winners but Ash manages to take control of his body sometime after. Ignoring the pleas from his ancestor to allow him passage and warnings of the consequences, Ash decides to erase his own history and calmly waits for the portal to close. The portal closes, which creates a time paradox: as Saiki is now trapped in the present, it is impossible for Ash to have ever been born. Thus, Ash ceases to exist, taking Saiki with him.
- Pyrokinesis - After killing and absorbing Saiki's powers, Evil Ash no longer possess his original green flames as he used to, but now possess black flames instead.
- Create Fire - Evil Ash can create dark fire from thin air.
- Fiery Attacks - Evil Ash can infuse his punches/kicks with dark flames for increased damage.
- Fiery Projectiles - Evil Ash can shoot out fiery projectiles and waves to attack distant foes.
- Fiery Movement - Evil Ash can move while leaving behind dark flame energy (which damages foes as he passes).
- Fiery Body - Evil Ash can ignite his own body on dark fire, without burning himself.
- Fiery Zone - Evil Ash can fill the area around him with damaging dark fire.
- Seal Techniques - Evil Ash can make enemies not use their powers for a duration.
- Seal Powers - Evil Ash can cut off energy sources from his enemies (thus preventing them to gather more power) for a duration.
As a result of the fusion, Evil Ash uses Ash's general techniques, but infuses them with darkness. He is also capable of performing a double Ventose and has a more extreme version of Ash's Germinal, done quicker and without having to perform the Sans-Culottes first. Furthermore, he has a Desperation Move in which he fills the screen with a series of dark explosions; this possibly mimics Elisabeth's NeoMAX, in which she performs a similar technique with light-based explosions.
- Diabolosis - The King of Fighters XIII
- Some unused files on The King of Fighters XII disc reveal the name Dark Ash, presumably referring to Evil Ash. It's possible that the presence of Evil Ash was being planned for the game.