Original Zero (ゼロ (オリジナル), Zero (Original)) is the sub-boss of The King of Fighters 2001. He is a high-ranking member of NESTS and the real Zero, for the Zero that appeared in The King of Fighters 2000 was merely a clone of him.
Zero was created because the supervising designer to his character claimed to be dissatisfied with Zero's design in 2000, hinting that ideas such as his black lion pet and this newer design were designed but not used. He is recognized by developers to be the first boss to surpass Krizalid (the supervising designer's previous character) in both fighting prowess and presence.
In direct contrast to his clone, Zero is loyal to NESTS to an extreme degree, to the point where, if he knew of his betrayal beforehand, would've likely opposed Igniz. In spite of his loyalty to NESTS, Zero is an honorable man, with a good example of this being the fact he likes raising children.
- Luminokinesis - Unlike his clone, Zero has several powers related to Light.
- White Hole - Unlike his clone, Zero can create a small hole that is strong enough to absorb inanimate objects.
- Energy Shield - Zero can create a shield of energy in front of him.
- Parenthood - Zero likes to raise children. Although a hobby, this skill displays his honorable and virtuous side.
- Scuba diving - Zero is stated to be proficient in scuba diving.
- 0 - The King of Fighters 2001
- The Testament of N.E.S.T.S - The King of Fighters 2002 Unlimited Match
- Igniz / Zero after Versus Regular Bonus - The King of Fighters 2
- Zero Clear Bonus - The King of Fighters 2
- Toshimitsu Arai - The King of Fighters 2001~2002 UM
- Taiten Kusunoki - The King of Fighters: World, The King of Fighters All Star
- Kaya Okuno - The King of Fighters: All Star (As Lady Zero)
- One of Zero's victory poses have him doning a cape, a reference to Alucard sprite from Castlevania: Symphony of the Night, understandable as both share the dark skin, white hair and black/blue clothes.
- The bladed portion of his armor has been called a "skirt" or a "cape," but seems to resemble a Javanese male sarong, only with blades sewn into the lining.
- Zero has an alternate version in The King of Fighters All Star, called Lady Zero. A tiny version of Glaugan (Zero's black lion) appears as part of her moveset, like her original version.
- Like his clone, he had no crouching attack animations, yet had standing attacks that must be guarded low, and could not crouch initially like typical SNK bosses. These animations and ability were gained as he was added in KOF2002UM, and is shared with his clone.