Given the Loads and Loads of Characters, it would only be fair that Mortal Kombat would have some popular characters under its belt.
- Although he's one of the "ninjas" who was riding off of Scorpion and Sub-Zero's popularity, Reptile established himself as the de facto dark horse among the fanbase since the original game, due to being the first Secret Character in the series (which sparked a great amount of interest in discovering and facing him, not unlike Akuma in Super Street Fighter II Turbo). Being an odd anti-villainous example of a Butt-Monkey, the Cosmic Plaything of the series, and sporting one of the better fight scenes and fighting themes in the movie has helped to give Reptile a big cult following among the fanbase. The developers seem to have caught up on this, seeing that, after several games of in-universe mockery, MKX throws Reptile two bones by giving him a rather heartwarming companionship with Kotal Kahn in the Story Mode due to both being their respective Last of Their Kind, and by giving him an Arcade ending where he discovers on Earthrealm that the Zaterran still exist, prompting him to pledge his loyalty to his race's empress. Along with a few other characters, his only appearance in Mortal Kombat 11 being through an Easter Egg in the Krypt and not as a playable character has been deeply mourned.
Mortal Kombat II
- Dan Forden, the "Toasty!" Man. Though his appearances are random and very brief, he is a well-known Easter Egg and often used in parodies of the series, and even made re-appearances in Mortal Kombat 3, Mortal Kombat 9, and Mortal Kombat 11. The fact that he is the key to finding Smoke in MKII also helps.
- Noob Saibot, the Wraith version of the original Sub-Zero, Bi-Han, was formerly this. Facing off against him was QUITE the grueling task (achieving 50 wins in a row), but it was seemingly well worth it. He especially became famous after Deception revealed he is the specter of Bi-Han, after the first game's events had Scorpion kill him. His popularity saw him back for MK9 and peaked from there. Even more so, come MK11, the developers upped his Deadpan Snarker tendencies, gave him a much more pronounced embracing of what he is, pure evil, and gave him a Guttural Growler voice that, despite sounding silly, is widely liked. He is also among the most popular characters to use in A.I. battles. With all of this in mind, it almost seems he is heading into Breakout Character territory.
Mortal Kombat 3
- The Cyber Lin-Kuei Cyrax, Sektor and Smoke are an interesting case in that while they were decried for being ridiculous ninja "klones" at first (who were accused of replacing Scorpion, Reptile and the human Smoke), the fans grew to accept them due to later games establishing personalities and excellent gameplay for them. MK9 later explored the human sides of all three, giving them a huge spike in popularity (with Cyrax and Smoke becoming the most popular). Come Mortal Kombat X, and the three became highly requested DLC characters that made the cut as part of the final DLC pack in the form of Triborg, with each representing three of the four variations, respectively.
- Kabal and Ermac were divisive at the time of their debut (vanilla MK3 and UMK3 respectively) due to being overpowered. After being toned down in later revisions, they moved over this way and returned for Deception.
- Deception saw Kabal turn back to the darkness and take command of the Black Dragon after his brush with death at the hands of Mavado in Deadly Alliance... which was contentious with fans. Any damage, however, was undone by MK9 fleshing out Kabal's backstory (being The Atoner for his Black Dragon days), making him Bash Brothers with Stryker on the NPD, and cranking up the tragic elements of his character by turning him into an angst-ridden man who thinks he's a monster post-disfigurement but still fights the good fight regardless. (Though NRS couldn't quite prevent him from reclaiming his MK3-era Tier-Induced Scrappy status, which followed him into 11.)
- Ermac, on the other hand, became something of an Ascended Extra, being responsible for teaching Kenshi (see below) telekinesis in exchange for breaking his mind control as well as becoming a heavy hitter for the heroes. The reboot then opted to turn Ermac into something of a Knight of Cerebus during his days serving as an enforcer for Outworld by having him telekinetically crush Jax's arms in his first appearance (thus necessitating Jax's switch to cybernetic limbs), while his Arcade Ladder ending dropped a bomb with The Reveal that one of the myriad souls comprising his being was none other than King Jerrod, Sindel's husband and Kitana's father who was slain by Shao Kahn. If that wasn't enough, X shows a more independent Ermac willingly serving Kotal Kahn while suggesting in a Mirror Match that Ermac additionally carries the soul of Shao Kahn himself inside him.
- Rain is another of the biggest examples of a darkhorse in the franchise. Originally a goofy Joke Character ninja Palette Swap who doubled as a Shout-Out to Prince (he wears purple and has control over storms because "Purple Rain"), he made his debut in UMK3. Although at first he was in Base-Breaking Character territory, when it was revealed that he was one of two characters from the original trilogy to not be playable in 9 (the other being Motaro, who actually does cameo in the story a few times), Ed Boon's Twitter was flooded with demands for Rain to be included as DLC. They got their wish, allowing him to head in this direction, and fan reception only improved when MKX featured him as a duplicitous member of Mileena's faction during the battle to usurp control of Outworld from Kotal.
- Khameleon from the N64 version of MK Trilogy pushed herself here when it was revealed that she was the only pre-existing character not playable in Armageddon. Fan outcry singlehandedly made sure that she had a spot on the roster in the Wii port of the game. It doesn't hurt that her story gives Khameleon a direct connection to Reptile, one of the most pitiable creatures in existence (namely, repopulating their nearly extinct race and turning him away from his servitude to the villains, the same party that seems to screw him over at any opportunity).
Mortal Kombat 4
- Reiko. The speculation his ending caused—the question of if Reiko was Shao Kahn in disguise/reincarnated—has a lot to do with it. The creators seem to have caught on to his popularity, as he makes an appearance as one of Shao Kahn's most trusted generals in Armageddon, has cameos in Mortal Kombat: Conquest and 9, and is depicted as a possible suitor to Mileena in the MKX prequel comics.
- Tanya was popular enough to be the only character introduced in MK4 who returned before Armageddon (a game which required the presence of everyone due to its nature), as she was an unlockable character in Deception. Being a new addition to the already popular female ninjas (Kitana, Mileena, Jade) helped, in addition to her treacherous personality. She even came back in MKX, at first as an unplayable character, later as a fully fledged DLC character with her own playstyle variations, while the story added more nuance to her traitorous ways through her alliance with Mileena.
Mortal Kombat: Deadly Alliance
- Kenshi (think Daredevil plus telekinesis) is one of the few characters from the post-Trilogy era to earn unanimous praise from the fanbase. How popular is he? Popular enough to make it into MK9 as DLC despite the roster mainly consisting of characters from the first three games note , and popular enough to return as a starter playable character in MKX.
- Nitara, the sexy, manipulative Vampiress had an intriguing appearance and backstory, but not much time to develop it further; in fact, a poll for which characters fans would've liked to see in MKX held at This Very Wiki had Nitara place fourth (behind Rain, Kenshi, and Motaro), a fair bit ahead of other popular gals such as Sareena and Khameleon. Nitara was even popular enough to get a cameo appearance in Mortal Kombat Legends: Scorpions Revenge and was announced to appear in the 2021 film.
- Frost, Sub-Zero's Distaff Counterpart and Deceptive Disciple, originally received much scorn after being introduced in Deadly Alliance (some even going so far as to say she'd "ruin Mortal Kombat"), but fans quickly warmed up to her. To the point she was included in the comics, made an appearance in MKX's Story Mode, and returned as a playable character once again in MK11.
Mortal Kombat: Deception
- Havik, the Crazy Awesome, Cloudcuckoolander cleric of Chaos whose repertoire of techniques has him twist and contort his body in odd ways, such as snapping his own neck to regain health; he's also notable for this moment where, if he falls from the Sky Temple stage, he yells "Man, this is gonna suck!" Though he's yet to make a reappearance as a playable fighter, Havik would later cameo in Noob's MK9 ending as well as play an important background role in the MKX comics.
Mortal Kombat vs. DC Universe
- The Joker got a huge ovation when he was announced, and his "Killing Joke" Fatality is one of the only ones people think didn't suck (so much so, that Shang Tsung borrows it in MK9.) A number of people also found him to be enjoyable and legitimately funny in the game, and his popularity eventually led to him returning in Mortal Kombat 11.
- Captain Marvel is a darkhorse thanks to this being his debut in a video game and for being one of the lesser known DC Heroes getting a chance to shine in a crossover.
- Deathstroke, who also gained praise for this being his debut in a video game and being a Ninjaesque assassin character, who would not be out of place in a main Mortal Kombat title.
Mortal Kombat 9
- Johnny Cage became a darkhorse thanks in part to borrowing his movie incarnation's personality (Film!Johnny was already being a darkhorse in his own right) and having his status as a well-meaning douche amped up to the point of hilarity. MK9 has quite a few CMOFs, and Johnny is responsible for most of them. Owing to his popularity, MKX ascended him to yet another Breakout Character by making him a Cool Old Guy and the best dad in the franchise and giving him his best CMOA ever (defeating Shinnok), while still keeping him as a source of great laughs despite the heartwarming rapport with his daughter and his improved badassery.
- Nightwolf is interesting as he started out as an Ethnic Scrappy due to his Game-Breaker and Magical Native American status in MK3 but was rescued come Deception and cemented himself with this position in MK9 due to having Took a Level in Badass and establishing him as a trustworthy ally of Earthrealm. This popularity even added him back in MK11 as a DLC character; most notably, this appearance of him has been acclaimed as it delved into his backstory, with his tribe, the Matokan, serving a Great Spirit and him earning the position as the tribe's "Nightwolf" (the leader and defender of the tribe) after he defended the tribe's pride from Kano.
- Another example of a character who was Rescued from the Scrappy Heap by the reboot is Kurtis Stryker. Before MK9, he was seen as a bland and boring character (if a Tier-Induced Scrappy in gameplay, especially after his Ultimate MK3 incarnation added the gunshot move) with an incredibly goofy design that reached Narm levels. His reappearance in Armageddon didn't exactly turn heads, despite his altered appearance. Come MK9, the creators threw him a bone by not only giving him a backstory very similar to the biography of John McClane, but also a much improved appearance that made him look sharper and more similar to a New York policeman. It also allowed him to have his crowning moments of ass-kicking in the story mode where he is able to take down the likes of Reptile, Mileena, Kintaro and Ermac using only his training in the force.
- Cyber Sub-Zero, Kuai Liang's Cyber Lin Kuei counterpart. After it was revealed Smoke wasn't the one kidnapped by the Cyber-Lin Kuei and programmed to help Shao Kahn conquer Earthrealm, Sub-Zero's new appearance as a cyborg was initially met lukewarmly, but soon grew more positive after the events of MKX revealed Quan Chi "rebuilt" Kuai's human self. It helps that, like Cyrax and Smoke (who is still a human as noted in the MK3 section), he never wanted to be part of the Cyber Initiative, while having gameplay differences from the human Sub-Zero that helped him stand out. His popularity would later include him in the Kombat Pack 2 for Mortal Kombat X, as a (not-so) secret variation for Triborg, with even more gameplay differences from Sub-Zero!
Mortal Kombat X
- Erron Black, The Gunslinger in MKX, was popular the second he was introduced in the prequel comics and fans immediately called for him to appear properly in game. His cowboy design, dry humor, neat gun tricks, and being revealed to be much older than he looks in his ending give him plenty of reasons to be a fan favorite.
- Of Cassie Cage's group, Takeda is the biggest example. His introduction in the prequel comics as Kenshi's son and one of Scorpion's students/his adopted son left fans impressed, especially after he broke out of his timid shell and found the will to kill (if necessary). His appearance in the game as a proud warrior, yet still a nice guy and arguably The Heart of Cassie's team, as well as the first fighter to extensively use whips for combat, has also helped his case significantly. In fact, he's one of the few "new generation" characters that didn't return for MK11 that have noticeably been missed.
- The Old Lady at the Marketplace stage—known as Blanche by the staff—is quite popular for a background character in a random stage because of the sheer amusement of watching the fight and being used as a weapon. She instantly became a Memetic Badass once it is revealed that she can beat people to death as a Stage Brutality. See for yourself!
Mortal Kombat 11
- An example of an inanimate one, the Joker's Batman puppet/hidden gun was immediately latched onto by fans. In particular, during Joker's back throw with the line "I'll save the day!" followed by several gunshots.
Mortal Kombat Mythologies: Sub-Zero
- Fujin, the God of Wind. Initially considered as just a fascinating take on the concept of more gods in Mortal Kombat, his appearance never turned much heads, even in MK4 or Armageddon (although his endings on both games are still considered to be decent). He started to gain more popularity with the release of MKX (both the comics and the game proper), serving once again as a companion to Raiden in the duty of protecting Earthrealm. However, this was nothing compared to his appearance in MK11's Aftermath expansion: after an intro between Raiden and Cetrion revealed something had happened to him, his appearance in the expansion as a playable character after 14 years has been widely acclaimed. His new characterization has further contributed to his popularity; it's revealed Fujin is Raiden's brother and his Foil in various ways, being much more affable and understanding of human life, and having an ending where instead of rebuilding a timeline by himself using mainly logic and love (Raiden's ending), he decides to live countless lives as a mortal (spanning realms, gender, race and faiths) to understand their lives better, allowing him to later on build a timeline where mortals can co-exist peacefully. Lastly, Fujin's much flashier moveset compared to Raiden has also given him a new group of fans.
- Sareena, a member of Quan Chi's Amazon Brigade who had a change of heart after Elder Sub-Zero spared her life. For a relatively minor character, she garnered a sizable fanbase and demand for a return. She was finally made playable in Tournament Edition (one of the two portable versions of Deadly Alliance) and Armageddon, where she forms a strong bond with Younger Sub-Zero. Being The Atoner and The Woobie also helps garner endearment points from the fans. To wit, a brief appearance in X as an informant/liaison for the heroes operating within the Netherrealm, complete with a Continuity Nod to how Bi-Han saved her during the events of MK Mythologies, had fans very pleased.
Mortal Kombat: Special Forces
- Tremor, who may perhaps be another of the greatest dark horses in MK (along with Reptile and Rain), is a member of the Black Dragon clan and the only ninja to not be playable in the main series until X. What makes this so exceptional is that he hails from what is undoubtedly the worst game in the series by an Outworld mile. Ed Boon himself commented (via Twitter) on Tremor's surprising popularity, calling him "the new Rain." While Tremor wasn't included in 9 note , Boon refused to outright say that Tremor would never be included again in the series. This became prophetic when X finally upgraded him to a playable character via DLC to the delight of many. AND HOW! From every aspect of his character (voice, costume, variations) oozing "BADASS", him having the highest amount of Brutalities (10!) and an ending that places him in the same tier as Physical Gods Raiden and Fujin, he finally got the honors he deserved.
Mortal Kombat: The Movie
- Reptile is one of the better things of the movie, especially his fight with Liu Kang. It might have been weird and out of nowhere, but many of the movie's fans have said it was actually the best fight in the whole movie; even better than the final fight!
- Trevor Goddard's performance in the movie as Kano was very well-liked by fans due to it adding a cocky, money-grubbing sleazeball personality to the flat depiction of the games. His performance was generally well-received by fans and even the creators of the games loved his portrayal so much Kano was actually changed from a Japanese-American with little character and no hair to an Australian-born thug with a full head of it (and a wicked widow's peak, to boot).
- Linden Ashby's portrayal of Cage is, as mentioned above, a dark horse, especially with the wittiness, the fight with Goro and how much he cares about Sonya... all of them things that eventually found their way into the MK canon as noted above.
Mortal Kombat: Defenders of the Realm
Malibu Comics' Mortal Kombat
- Hydro, the water-based Lin Kuei warrior and partner to Sub-Zero who appears first in the Malibu comics. He's a very popular character with fans, enough to be included in MK fan works such as the numerous M.U.G.E.N-based Mortal Kombat Project full games and even appeared in Mortal Kombat: Legacy as a cyber-ninja.
- Bo, the completely normal but damn huge Scary Black Man that Cage hires as Liu Kang's bodyguard, is this as well. Especially the way he beats Reptile in Tournament Edition #2 with a broken arm to boot.