Obviously, Mortal Kombat features a lot of fighting since it is a tournament fighting game. So, heroes fight villains, heroes fight heroes, villains fight other villains: any kind of match-up is possible. This is also the case for the Mortal Kombat mythology's expansive lore.
Some fights are not just randomized matchups, some fights are impactful and emotional with consequences and payoff. This is due to different characters having rivalries across the realms. Over the many games, characters have developed long-lasting and/or iconic conflicts that have fans cheering for more.
Kitana VS Sindel
Family drama is always some of the most tragic drama. In this case, it's even worse because Kitana's own mother is resurrected as an evil and very powerful being. Kitana fighting her own mother is bad enough but at least she's only evil because Sindel is bewitched, right?
Incorrect. In a divisive twist, Sindel is fully restored only to reveal that she was never bewitched. She actually betrayed Edenia to Outworld for Shao Kahn; acting as his most loyal Queen. This makes her rivalry with the good-hearted Kitana even more tragic since Kitana has already gone through so much.
Johnny Cage VS Goro
Technically, this rivalry was never a thing in the games. However, after Johnny Cage's confrontation with Goro in the 1995 Mortal Kombat movie, references to Johnny Cage and Goro's hate for each other have been sprinkled in the games. Even Johnny Cage's five hundred dollar sunglasses line from the movie is tributed several times.
In Mortal Kombat: Armageddon, the main menu always shows two rivals. One of these screens featured Johnny Cage and Goro; so while this rivalry was not a game invention, it did create a legacy.
Kitana VS Shao Kahn
It's easy to see why Kitana hates Shao Kahn; he invaded her realm, murdered her bio father, and stole Kitana as his own. Then when she was considered too weak for him, he had Shang Tsung create a monstrous clone mixing Tarkatan blood thus resulting in Mileena. Kitana was then cast aside by the evil Emperor.
That's why Kitana defying and later on overthrowing Shao Kahn has always won the heart of fans. Everyone wanted Kitana to get retribution and she certainly did. In Mortal Kombat 11, she defeated Shao Kahn in combat, blinded him, then won the title of Kitana Kahn.
Kotal Kahn VS Shao Kahn
Though he is no saint, Kotal Kahn was an instant improvement of an emperor after Shao Kahn's demise. When Shao Kahn was making his triumphant return due to time travel in Mortal Kombat 11, everyone was excited to see the Kahns fight. Netherrealm Studios did not disappoint in that regard.
In the eleventh game and its Aftermath expansion, Shao Kahn and Kotal Kahn have a few confrontations that really steal the show. They are two massive titans who shake the ground with each impact and even in the cinematics, their fights are brutal and powerful. It shows why Shao Kahn is one of the most powerful villains even after eleven games.
Kitana VS Mileena
Kitana definitely has the most rivals and the one that most people think of is her dynamic with Mileena. Being her evil clone who devours people alive and is everything Kitana isn't, it's no wonder Kitana hates her. On top of that, Mileena is always trying to kill Kitana so she can replace her.
Sadly, their rivalry despite being famous does not get enough spotlight. If Kitana and Mileena return in a Mortal Kombat 12, their rivalry should be given more time to expand.
Raiden VS Revenant Liu Kang
Another tragic rivalry that all spawned because of messing with time. Due to an accident by Raiden, Liu Kang was killed in Mortal Kombat 9. Liu Kang would return as an undead warlord known as a Revenant who serves and later on rules the Netherrealm.
Raiden viewed Liu Kang like a son so seeing them drift apart to opposite positions is sad. However, it does make for some powerful and memorable fights between the two. The final confrontation between them in Mortal Kombat 11 is by far the best.
Kuai Liang VS Bi-Han
More family drama with the first Sub-Zero being a heartless villain and the younger one being an Earthrealm champion. Bi-Han, the older brother, ends up betraying everything Kuai Liang stands for, especially when B-Han returns as the dark specter known as Noob Saibot.
Much like Kitana and Mileena, the Sub-Zero brothers do not have enough time together in the story. Whenever they do appear, it is a sad but epic tale of two brothers battling but could definitely benefit from more development of their rivalry.
Liu Kang VS Shang Tsung
Hero-versus-villain rivalries don't get much more classic than this. One is the Chosen One of Earthrealm and the other is the champion of Outworld. In the games, the events that lead to their hatred for one another is different, but they usually end up being mortal enemies. They even competed for godhood in Mortal Kombat 11.
Their most personal conflict would be in the 1995 movie. In that, Shang Tsung murdered Liu Kang's brother thus making Liu Kang's journey more emotional. Events happen in the 2021 movie that also set up the hatred between Liu Kang and Shang Tsung for sequels.
Sonya Blade VS Kano
One of the most famous of rivalries in gaming; Sonya Blade and the sleazy criminal Kano. Why Sonya hates Kano so much tends to change depending on the timeline, movie, and retcon. However, it usually involves Kano betraying Sonya somehow combined with the fact that he's practically inhuman.
For eleven games, Sonya and Kano's relationship has had many heights until his death in Mortal Kombat 11. In the 2021 movie, Kano won the hearts of fans as one of the best characters due to his hilarious, if not problematic, portrayal. However, he betrays not only Sonya but all the Earthrealm fighters; some things just never change.
Scorpion VS Sub-Zero
Of course, when it comes to Mortal Kombat rivalries, none are as famous as Scorpion and Sub-Zero. Hanzo Hasashi of the Shirai Ryu and Bi-Han of the Lin Kuei, two grandmasters who already hated each other. Then Bi-Han murdered Scorpion's family and Hanzo himself, thus beginning a war between these two ninjas.
Hanzo became Scorpion and vows to avenge his family and clan. For over eleven games, Scorpion and Sub-Zero have remained the poster children. Arguably, the new 2021 version of Mortal Kombat makes their rivalry even stronger by making Bi-Han so surprisingly ruthless and evil. Their wild powers and designs help but their interconnected backstory and lore have made them icons.