I have taken most of this info from the Mortal Kombat plot guide faq, by Gavok. On some, I have given my own views, based on endings that most likely happened, where nothing later suggests that they didn't. I have deliberately missed out Konquest in MKD, as I'm not sure how much of that should be taken as canon, and could be here all day.

Official, canon fights.

MK1. This is gonna be hard, as MKSM could change things.

Before the tournament (shown in Tobias's official MK1 comic) Kano and some thugs attack Johnny Cage. Liu Kang steps in to help Johnny, and they beat Kano and co. This is the first meeting of Liu and Johnny.

Scorpion fought and killed the older Sub Zero, as we all know.

Liu Kang defeated Goro, to become the champion of MK. He then goes on to beat Shang Tsung.

Johnny Cage fights Reptile, and Sonya fights Kano in the intro to MKSM.

This is most likely retconned, but in Tobias's MK2 comic, Johnny, Sonya and Kano teamed up to battle Goro. The trio were winning before the island crumbled, and Raiden could only save Johnny.

MK2. Again, MKSM may retcon some of these battles.

Sub Zero defeated an unknown opponent and spared his/her life. Most likely a fellow hero. This is what makes Scorpion first suspect that this Sub Zero is NOT the same man he killed before.

Scorpion the defeated the younger Sub Zero (perhaps giving him the scar), and realised for sure that it wasn't his old enemy back again.

Kitana fought and killed Mileena.

Liu Kang most likely defeated Shao kahn. MK3 tells us that Liu is the biggest threat to his rule over Earth, and if Kahn hadn't lost to someone, he wouldn't have needed the plan of ressurecting Sindel.

I'm not sure whether this is canon, but people say that Raiden fought and killed Kintaro. Others say it was made up by someone other than Midway. Don't know for sure.

Before the tournament, (in Tobias's MK2 comic) Shang Tsung, Baraka, Kitana, Mileena and Kintaro attacked Johnny Cage. He was helped by Jax and a soldier called Beran (who Mileena killed). The fight went to a non finish when the other heroes arrived, and the bad guys went back to Outworld.

This goes against the game story, so it most likely didn't happen. But Scorpion stepped in to beat Reptile, who attacked Sub Zero, saying he was now this Sub's protector.

MK3/UMK3/MKT.

Sub Zero defeated Cyrax, and messed about with the cyborgs programming.

When Jade turned against Kahn in favour of Kitana, she fought Reptile, who'd also been assigned to get her. We don't know the result of this for sure, but I suspect Jade won, as Kitana managed to escape from Reptile.

Shao Kahn defeated Kung Lao. Originally, this was going to be Kung Lao's death scene, but was retconned.

Shao Kahn also most likely killed Rain, when the ninja turned against Kahn. it's in Rain's own ending, and nothing so far contradicts it.

Sonya beat Kano, and threw him from the roof of a skyscraper. Kano was saved by Motaro.

Kitana was the one who made Sindel regain her memory. This was most likely during a fight, as Sindel was pure evil before.

Either Liu Kang or Raiden defeated Shao kahn. Most likely Liu, but Raiden did fight the Emperor.

Scorpion was defeated, either by Kahn, or a minion (such as Shang Tsung), and sent back to the Netherrealm. Scorpion originally joined Kahn, but turned against him.

Some time between MKT and MKDA, Sheeva killed Motaro, and tried to attack Kahn. But Kano betrayed Sheeva, and the Emperor killed her.

Some time between MKT and MKDA, Sektor killed the Lin Quei Grandmaster, to try and take leadership for himself. He was then defeated by younger Sub Zero, who took charge and reformed the clan as a force for good.

MK4/MKG.

Kitana again beat Mileena, but this time had her locked up.

Liu Kang destroyed Shinnok. It is said in MKD, Liu's Tomb, with his 4 victories.

Jarek attacked Sonya on a mountain, but missed, and fell to his death.

Scorpion defeated Sub Zero, believing he murdered his family and clan. Sub Zero managed to explain that he wasn't the man who did this. Quan Chi came out and admitted it was him, and banished Scorpion to the Netherrealm, but he himself was dragged there too by the ninja. Scorpion had beaten up a weakened Quan Chi at least once in the Netherrealm. This causes Quan to ally with Dramin and Moloch. Some time between then and MKDA, Quan Chi beat Scorion, and threw him into a pit of acid, sending him to the Netherrealm yet again.

There is an official MK4 comic, which may or may not have other fights explained. I've never read it.

MKDA/MKTE.

A delusional Reptile fought Nitara. Not sure who won (if anyone) but Nitara managed to convince him to join her. Reptile then attacks Cyrax, and destroyed his arm panel, though Cyrax comes out on top.

Shang Tsung and Quan Chi killed who they (and we) beleived to be Shao Kahn, but it was in fact a double. They then went to murder Liu Kang.

Noob defeated Goro, who was originally written dead, but now saved by Kahn.

Mavado defeated Kabal some time before MKDA, before the Deadly Alliance recruited him.

Li Mei fought Kano, who enslaved her village for the DA. Quan Chi stopped the fight, but she was doing well. this is when he made the false deal about the tournament, and her village.

Frost attacked Sub Zero, and took his Medallion. But she couldn't control it, and the overload of power froze her to death.

Jax killed Hsu Hao (nothing to say otherwise) before Jax joined the other heroes in their ill fated battle.

Mavado deafeated Kenshi, and got his reward, to fight Kano. Again, there's no contradictions, so it looks like he killed Kano. Mavado himself was then defeated, possibly killed by Kabal some time later.

Li Mei must have done well enough to think she won the DA's "tournament". She then finds out it was a trick, and her soul is put into an undead soldier. She is saved by Bo Rai Cho.

The DA defeated and killed Kung Lao, kitana, Johnny Cage, Sonya and Jax. They then beat Raiden himself, before turning on each other. Quan Chi won, but Onaga interrupted things. they and Raiden couldn't beat Onaga, and Raiden blew himself up as a failed sacrifice. We don't know if the DA survived this or not. Scorpion was thrown into a Soulnado by Drahmin and Moloch, who attacked him as he tried to catch Quan Chi. Scorpion is saved by the Elder Gods, becoming their champion.

MKD. All speculation at this point. Endings give us clues, but we won't know for sure until MK7 what exactly happened.

MKM. Before MK1.

Older Sub Zero kills a human Scorpion, starting the whole revenge/rivalry storyline. He then defeated Fujin, and the Gods of fire, earth and water.

Classic Sub Zero then kills Kia and Jataaka, but spares Sareena's life after beating her. They both then defeat Quan Chi before Shinnok murders Sareena. Old Sub then fought Shinnok, and couldn't beat him, but did remove the amulet. Shinnok turned into a giant monster and chased him, but Raiden opened a portal, which Classic Sub Zero escaped through.

MKSF. Also pre MK1.

Jax defeats Kano, Jarek, No Face, Tassia, and Tremor, who had escaped from jail and killed other soldiers.

MKM: Subzero fought Scorpion in the Netherealm and defeated him while on his quest for Shinnok's amulet.

MK1. Scorpion and Subzero didn't fight. Scorps just killed him.

MK2. Subzero most likely defeated Reptile and spared his life. Cuz think about it. He was sent to kill Shang and Reptile is his personal protector. Also Boon (or another Midway official) said that even though you fight Kahn in the mk2 game, storywise Kahn never actually fought anyone until mk3.

I believe MKSM's intro shows Scorpion and the older Sub Zero fighting. Like I said, this game may retcon past events.

I guess it's possible younger Sub Zero spared Reptile after beating him. But it would make more sense him fighting, defeating and showing mercy to a fellow good guy during a standard tournament bout. The identity of this opponent remains unknown.

Boon did say that nobody fought Kahn until MK3. But the MKD background for Liu's Tomb has medallions awarded to his FOUR MK victories. Since he was killed before MKDA, it would make most sense to assume MK1, MK2, MK3 and MK4 (there's nothing to say they refer to any other achievements).

Boon probably said this before MKD (correct me if I'm wrong), and we all know what MK's like for retconning things. But it COULD BE POSSIBLE that Liu and the others simply did enough to save the Earth without actually fighting Kahn himself, thus Liu remains champion and number 1 threat. The bad guys must have lost somehow, or the Sindel ressurection plot to invade Earth for MK3 would not be needed.

i like the idea of subbie vs. reppy and then scorp saves subby even tho hes winning. i just assumed that the "unknown warrior" was jade or a hidden character

It had to have been reptile as the unknown warrior.

And the only reason Kahn considered Kang his number one threat was because he learned of goro and Tsung's defeat at Liu's hand as well as Kang beating most of Outworld warriors that Kang poses more of a threat to his Conquest of Earth

Scorpion beat up Reptile in the MK2 comic (written by Tobias), after he attacked younger Sub Zero, before the tournament when Shang's warriors attacked Johnny Cage. The comic says that this is where Scorpion declares himself to be this Sub Zero's protoector, to make up for killing the older one.

But as it goes against the game's story, the only way it COULD have happened is if Scorpion beat Reptile away, still beleiving younger Sub to be the older Sub, and not wanting someone else to get him before he did.

The "unknown opponent" remain that, unknown. The MK2 characters it CAN'T be are Scorpion (watched the battle), Shao Kahn, Kintaro, (bosses), Liu Kang (or Sub would be MK champ), Shang Tsung (who he was meant to kill) and I guess Kintaro and Raiden. This gives us NINE candidates (if we assume MK2 Noob is canon) for who it could be. I still think it's most likely a fellow good guy.

how bout this:

in mk who did:

stryker
nightwolf
jax
scorp
ermac
noob

fight?

in mk4 who did:

kai
fujin
reiko
jax
tanya

fight?

in mkda who did:

nitara
sareena
blaze

fight?

(i wont do mkd b/c no-one really knows)

how bout this:

in mk who did:

stryker
nightwolf
jax
scorp
ermac
noob

fight?

in mk4 who did:

kai
fujin
reiko
jax
tanya
johnny cage

fight?

in mkda who did:

nitara
sareena
blaze

fight?

(i wont do mkd b/c no-one really knows)

nobody knows for sure about those characters, though it is more than likely that Cyrax fought Blaze in MKDA. Sareena had nothing to do with MKDA, she was in Earthrealm the whole time. Nitara probably let Cyrax and Reptile do all of her work for her. in MK3, Scorp probably just wandered around Earthrealm for a while until he decided to whack Shao Kahn because he was going after Sub, but he died, it was probably Motaro or Shang. Noob was fighting for Shao Kahn, under Shinnok's orders, and switched sides during some point. thats all thats known