The original Sub-Zero in Mortal Kombat is Bi-Han.
Bi-Han is a member of the Lin Kuei, a Chinese clan of assassins with cryomantic abilities. He appears as Sub-Zero in the first Mortal Kombat game. After his death, his younger brother Kuai Liang assumes the Sub-Zero identity and becomes the version most associated with the heroic side of the character.
Bi-Han does not simply disappear from the series. He returns as the wraith Noob Saibot, whose name is derived from the surnames of series creators Ed Boon and John Tobias written backward. This transformation is one of the franchise’s recurring links between its character roster and its original creative team.
Because both brothers use the Sub-Zero name, answers that identify only “Sub-Zero” are incomplete when a question asks for the original character’s personal name. Bi-Han refers specifically to the first bearer of the mantle.