Which Mortal Kombat character is the elder Sub-Zero’s younger brother?

Kuai Liang is the younger brother of the elder Sub-Zero, Bi-Han.

In the classic Mortal Kombat continuity, Bi-Han is the original Sub-Zero and appears in the first game. After Bi-Han becomes the wraith Noob Saibot, his younger brother Kuai Liang takes up the Sub-Zero identity and becomes the series’ principal ice-powered hero.

The two brothers are often confused because both use the same codename. Bi-Han is the Sub-Zero who is killed by Scorpion in the original game’s backstory, while Kuai Liang becomes the Sub-Zero playable in Mortal Kombat II and many later titles.

Continuity changes in Mortal Kombat 1 give the characters different roles in a new timeline, but the established classic storyline explains the distinction most clearly. Kuai Liang is also known for his association with the Lin Kuei and for eventually opposing its leadership under increasingly severe circumstances.