The_None's Giygas. Put simply, if you once feared but then grew desensitized towards Giygas, this version of him will rekindle that fear, permanently. He can summon stuff like headcrabs, as well as employ his endless repertoire of PSI-powers, at seizure-inducing levels and plays horrible sound clips of agonized wailing and screaming at completely random intervals. One of his special moves involve throwing the victim into one of two stage fatalities from Eternal Champions: Challenge From The Dark Side (they function like quick time events to make it easier), and they are signaled by a red flash picture of Spengbab. When a new round starts, it looks as if you're fighting someone completely different, like Youmu, but SPENGBAB IT'S A TRAP. And when he wins...he'll either flash Gorny stuff at you, a Michael Jackson pic that GOES MAD and...Smile.JPG.
But Wait, There's More! Other deathtraps of his involve a Doom homage, shooting monsters and Hol Horse & J. Geil's Hanged Man while trying to avoid shooting Slendermannote which oddly has Shaquille O'Neill's face...and another is the closet scene from Ao Oni. His other winposes can remind people of bizarre childhood nightmares; such winposes include a hideous face approaching the screen while appearing and disappearing randomly, bizarre lines of text in the same language as the Marker Symbols from Dead Space, a computer shutdown advisory, a dark, empty hallway, another hallway culminating in a faceless man jumping you, "THE DAWN IS YOUR ENEMY", three gory death screens from Waxworks, a still of the parking lot from Portal, eventually having a giant thing crawling towards the camera, and...this.
As if nothing could get worse up to this point, Ced Soum edited this character and named it )4:E?CM?P?CPe?dkd?CPCP?fRMG84, which, in addition to being more disturbing than the original, utilizes the Super Null creation method. Nothing could get worse from here, right?
An obvious example would be Andres Borghi's original creations. In particular is Noroko, the Stringy-Haired Ghost Girl. She has an instant killing desperation that is a literal screamer, and a win pose where she attempts to "escape" from MUGEN.
Dee Bee Kaw, while normally very humorous, is actually rather disquieting when he wins via the Shun Goku Hamusuta Satsu, because he stands over his opponent's lifeless body and starts laughing maniacally while the screen goes from black to red.
Jinmen from Devilman is just as creepy as he is in his source material. He's a giant humanoid turtle whose shell is composed of the sorrowful faces of his victims. He has a super where he drags an opponent into a murky pool of water, where he restrains and attacks it while helpless. He can also trick an opponent into killing one of the faces, which bloodily explodes and causes damage. He even has a finishing move where he eats the opponent and adds its face to his collection.
Gurospoo. A joke character based on an old meme called "Devil Spoo" whose attacks, moves, super and hyper attacks consist of him cannibalizing characters and turning their extremities into extremely powerful abominations. And adding an extra ingredient to the recipe: he has a special hyper attack where he teleports the opponent to hell.
Crazy Catastrophe's 11P can be seen as this. It offers seven 'levels' of full screen stuff happening all over, with low-pitched voices from Mizuchi and Orochi, later joined by female laughter and voices usually found within Oni-Miko... the fourth and seventh levels even has the screen alternate colors between red, green, blue and white, while some of the kanji include 'Metsu' (destruction) and 'Satsu' (Murder).
Dark Donald & Excellent Donald have screamers coded into them at the start of the second round, starting by tricking the player into believing they are playing a different character, and then an image accompanied by a loud scream will appear on the screen, some of which are the scary girl from the "Scary Maze Game", Pennywise, Sonic.exe, etc.
The very existence of the Dragon-Tiers characters. They are actually extremely powerful viruses that are capable of seriously and permanently damaging not only a computer, but also other types of local networks, from a city network to, hypothetically, a satellite network. They are considered the last tier of MUGEN characters and also the most dangerous types of characters. Fortunately, as a result of this fact, none of them have been made available to the public, and the creation method used on them is unknown.
Everything about Kyouki (not to be confused by the unrelated porn-character Kyouko): An emaciated, towering monstrosity with a mask-like face, black sockets for eyes (except in its win-pose), and matted black hair. When you KO it, it disintegrates into a swarm of possessed-looking baby dolls, followed by a cutscene of it getting closer and closer to the screen, ending in a static image of its mask-face. It then reappears, with YOU KO'd instead as it does its disturbing win-pose.
A tamer example, but one of RAHLONNIR's Punisher's supers has him run over opponent with his vehicle, take them inside said vehicle, and then starts to rip them apart with his gloved hands, complete with gory sound effects.
Felix the Cat is normally not all that bad. Just as innocent and fun as he has always been. However, in the version that comes with Brergrsart's VHFSMACVUSMRRM fullgame/compilation, he will gorily tear off his own face when KO'd, just like he did in the infamous russian bootleg of his game. Joel's reaction is the same as it was back then.
Nijikaku is an incredibly bizarre Japanese MUGEN fullgame based off of 2chan and its various memes. While most of the game is fairly tame despite its oddness, the game has some very grotesque, violent and downright disturbing imagery as well. Examples of this include Gurocure, a team-based character that can make its opponent slowly fade away into nothing with some of the creepiest piano music ever and can also feed them to a monster made out of what is presumably flesh, Sattin, a parody of Satsuki that uses a jump scare in one of its supers, then crushes its opponent, and Manamana, who has a super where she hammers nails into her opponent's penis, on-screen. And this is only scratching the surface of some of the more disturbing parts of the game.
SCP-999 is usually a heartwarming character to play as or play against, with all of its moves dealing no damage and instead making the opponent happy. However, in order to give them the "happy dance KO" state, the opponent must be susceptible to custom states, meaning that they need a hurtbox without hyper armor, or be vulnerable to reversals. Should neither be available and the opponent still continues to function normally even after their happiness is filled, then after a few seconds SCP-682 will suddenly drop out of the sky from nowhere to instantly crush the opponent in a Jump Scare. It doesn't help that 682's sprite has exposed flesh and bone, further adding to the Mood Whiplash.
Chuck Norris is usually a humorous character, but running him against himself will result in an epilepsy-inducing rainbow seizure effect, which generates a fake pop up saying "Chuck Norris isn't going to kill his enemy... He's going to kill MUGEN!" Leaving the match running for 3 seconds after this results in a TV static effect being applied, and the game crashing after a while. While the context of two Chuck Norris' ceasing to exist is funny, it's a surprisingly nightmarish thing to witness for yourself.
There are a surprisingly huge amount of characters based on content from kids' media that are either compatible with Mortal Kombat's fatalities, or can perform said fatalities (or both).
The most famous example is DG's The Powerpuff Girls (specifically, the 1998 one), where Bubbles, Buttercup and Blossom having zero qualms on straight up murdering their opponent if they wanted to and in a rather gory fashion. note To put this in perspective, the only time the Girls have shown this kind of brutality, at least canonically, was their 1992 pilot Whoopass Stew.
Legend of Sebas's Baron Dimanche & Baron Mercredi, in particular his victory pose animations, which consist of a compilation of scary snippets taken from horror movies, obscure videos and montages, accompanied by disturbing sound effects that mix screams with the sounds of of voices saying things, accelerated & inverted.
sm666 had a jumpscare coded into one of its animations, which works as a victory pose.
There is a rumor going around the Mugen community that shows us a little about Mathrus' disastrous power: Ced Soum (a well-known creator of chapie characters in the MUGEN community) was part of an alleged group of Russian MUGEN content creators (Including Urak, who is said to be the original creator of Mathrus) who were totally dedicated to creating dragon-tier characters and anti-malware characters (according to his own words, there are three more dragon-tier characters produced by this group, known as Doxa, Wendel and Louvan) which operated via the Skype application. It was precisely from there that he obtained a copy of the original version of Mathrus, and decided to test it on a computer at a school he was studying at, sneaking into the school's information room and infiltrating one of the computers to test it. According to him, the test caused a blackout that knocked out the power grids in his town, leaving the entire town without electricity for 24 hours. Ced managed to escape before he was captured.
Summarizing everything so you don't have to read this long text: Mathrus was so powerful that he was able to cause a blackout across an entire city and crash the communication networks of an entire high school (if this is confirmed true).
The character XXXXX (a frost cheapie-style character who resembles Kirby's character Zero) was inspired by a nightmare his creator had.
As expected from a character with a disturbing thematic, his theme is also quite fear-worthy.
As if The_None's Gigyas wasn't disturbing enough, Unreachable and HellToast's versions managed to prove that bad disasters can get even worse.
Sadist Zero Final on its own is a pretty morbid Donald edit, but when his 12p (also called "Level X/Unknown") is activated, this is taken to another level.
Continuing to talk about disturbing and unsettling characters, KingDemonic666's KillAll also deserves a good honorable mention here.
When we select this character in his first color palette (1P) to fight, what do we see? A Ronald CUT IN HALF (practically dead), Japanese words written in purple, an image of Ronald with bleeding eyes (which is hidden by the other visual effects), energy projectiles borrowed from Crazy Catastrophe (apart from the sound effects) and the Killer Donald theme in reverse, which has a depressing and disturbing feel.
His last color palette (12P) as well as his last power level also deserve a mention in their own right. We come across the spirit of Donald (with purple wings and a halo), accompanied by Orochi (who could possibly be Hasthur or C.C) and Colonel (who could possibly also be Dark Excellent Colonel), all in purple and with disturbing red eyes, while Ronald stares down into the void. At least the epic battle theme it has on this palette makes up for the creepy feel that KillAll naturally presents.
Because it's naturally an edit of a supremely powerful character, things don't change much for KillAll when we compare it to Killer Donald (the inspiration character from which it originated) except for the small and simple fact that this edit of Ronald can win an incredible 512 ROUNDS, SIMULTANEOUSLY, against any opponent below his level. Who would have thought that an iconic clown from a fast-food franchise could go this far?
Some of the various edits of Ronald McDonald created for MUGEN may fall into this topic. However, some of them take the cake when it comes to the most unsettling aspect of MUGEN. And starting with the playful one and as a fitting honorable mention, we can mention:
666, created by Vergil The God Of Sparta, especially its latest version with the 12p activated. To begin with, one of his attacks involves quickly grabbing the opponent, throwing them to the ground, and then brutally and rapidly tearing them apart. The stage begins to shatter like glass during this attack, and the colors of the hitsparks change from a light form to red, green, and black.
Another one of his attacks involves him materializing Sonic.exe (who is facing away), turning towards the opponent, and unleashing a barrage of energy strikes that take on the appearance of a red skull. Disturbing screams can be heard at a high volume, creating a chilling mix of sounds.
Just like DD & DEX Donald, he has encoded screamers within him. But one detail makes all the difference here: unlike the others, whose screamers are coded to be invoked at the beginning of a second round in a fight, 666 can summon these screamers at any moment during a fight, in random ways. Moreover, they instantly kill the opponent and obliterate whatever remains of them through a massive explosion of red and black energy.
