Probably Liu Kang or Raiden.
Quan Chi was pulled into the Netherealm by Scorpion along with Shinnok's Amulet. Without it, he was powerless so he was most likely killed or defeated by Liu Kang or Raiden.

Cyrax, Kung Lao, Liu Kang, Johnny Cage, Raiden, Scorpion, and Fujin's endings did happen.

Kitana, Sonya and Reiko's endings are all MAYBE situations up to this point. Eventually we'll find out who's ending happened and who's didn't in MKD or a future MK.

everyone else's ending didn't happen for these reasons:

Mileena (Kitana doesn't die).
Baraka (Quan-Chi didn't kill Shinnok and rule Outworld with Baraka)
Jax (well, Sonya's alive and so is Jarek)
Sub-Zero (Quan-Chi's still alive)
Jarek (Sonya's still alive)
Tanya (Liu Kang's still alive and Shinnok didn't win)
Kai (Raiden still has his staff)
Reptile (he's still alive, and Shinnok didn't win)
Shinnok (come on, have some common sense)
Quan-Chi (he didn't kill Shinnok)

and as for who beat Shinnok....as Xiaohu said, it's a toss up between Liu Kang or Raiden. I like to believe it was both of them. A two on one fight.

PsychoFight Wrote: Kitana, Sonya and Reiko's endings are all MAYBE situations up to this point. Eventually we'll find out who's ending happened and who's didn't in MKD or a future MK.

Yeah, it was assumed Kitana and Sonya's endings were true, but since Mileena and Jarek are in Deception they probably didn't happen. Unless they were resurrected which hopefully isn't the case.
And Reiko....no one knows what his deal really was.

It surprized me to learn that Reiko is Shao Kahn.

I think Liu Kang won. Because he won all the others why not the fourth

Nightwolf1115 Wrote: It surprized me to learn that Reiko is Shao Kahn. I think Liu Kang won. Because he won all the others why not the fourth

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I thought Quan Chi killed Shinnok in the Netherealm between MK4 and MKDA. Scorpion took Quan to hell in his ending. And Raiden banished Shinnok to the Netherealm after Liu Kang had won.

Quan had the real amulet so Shinnok was powerless and defeated him. Then Quan escaped and DA happened.