The lore and backstory of the Mortal Kombat franchise indicates that there has been more than two people known as Sub-Zero. As a member of the Lin Kuei, Sub-Zero's origins have remained mostly shrouded in mystery since his debut in the first game in the series. When Sub-Zero returned in Mortal Kombat 2, he was revealed to have taken the name used by his elder brother who had perished at the hands of Scorpion during the events of the first game. Later Mortal Kombat entries went even further in dealing with the brothers and their usage of the title.
Bi-Han is the original Sub-Zero of the Mortal Kombat franchise and is the one that fans remember from the first game. After the events of the original Mortal Kombat, he returns to the series as Noob Saibot, a Netherrealm wraith and member of the Brotherhood of Shadow who often works as an antagonist. Replacing him in the role of Sub-Zero is his brother Kuai Liang. Before taking his brother's title in his honor, Kuai Liang formerly operated under the code name Tundra within the Lin Kuei. Kuai Liang simply taking his brother's name for himself opened the door to the possibility of other Sub-Zeroes having existed prior to the brothers fans knew.
As one of the few games in the Mortal Kombat series to fully explore the depth of its lore, Mortal Kombat Deception featured a Konquest Mode in which players took control of Shujinko through the vast world of the MK series. Players start at Shujinko's youth before progressing through the events of the franchise as he undertakes adventures in the background of the main plot. During this adventure, Shujinko encounters familiar faces from Mortal Kombat's history as well as predecessors and ancestors of other characters. One such encounter occurs early in the story when Shujinko encounters a familiar, blue-clad warrior of the Lin Kuei.
Sub-Zero As A Title In Mortal Kombat
Throughout the course of Konquest Mode, Shujinko uses the powers granted to him by Damashi - the avatar of Onaga - to replicate the techniques of other fighters. Among the first fighters Shujinko is able to mimic is Sub-Zero, as he visits the Lin Kuei's Fortress once he is able to leave the gates of his village. However, players may realize that the timeline of events prevent this Sub-Zero from being the same as either Sub-Zero they may know from playing the game itself.
In Shujinko's in-game Bio Kard in Mortal Kombat Deception, one of MK's original creators and artists John Vogel confirms that this Sub-Zero is an ancestor to the others. This is explored further in the latest installment in the series which may have revealed the identity of this particular Sub-Zero and his relation to the others.
Mortal Kombat 11 features unique character introductions across the entire roster before a fight, including when characters face themselves in mirror matches. Sub-Zero's introduction quotes when facing himself will sometimes refer to the other Sub-Zero as a clone of some kind. However, there are special introduction sequences where one Sub-Zero may be referred to as Bi-Han from another timeline or even his grandfather, demanding of Kuai Liang, "Defeat me to earn my mantle."
Noob Saibot - the former Bi-Han - also references this relation in an exchange with his younger brother as he tells him to "disown his name" in response to how Kuai Liang has "disowned him in every way." Kuai Liang responds, "The name was Grandfather's first," confirming that the title had been passed down through at least three generations.
Mortal Kombat's extensive history and multiple timelines has woven a web that connects characters through multiple generations. Perhaps with the timeline reset at the end of MK11 Aftermath, fans may get the chance to see the ancestors of their favorite characters in action. With the references made in both the franchise's original timeline and the current timeline, it seems likely that a new installment in the Mortal Kombat series may yet include the presence of the first person to hold the mantle of Sub-Zero, as the franchise continues to prove that time freezes for no man.