Haohmaru (覇王丸, Haōmaru; also can be written as "Haoumaru") is the main protagonist of the Samurai Shodown series and one of the series's most known characters, the other being Nakoruru. He was introduced in the first Samurai Shodown and continues to appear in every title of the series.
Though he is a swordsman with no loyalties to any lord (rounin, lit. a wanderer), Haohmaru has a "samurai spirit" which is often stressed in the series. He is also often accredited to defeating most of the series's villains. 
His character origin was originally based around the famed swordsman, Miyamoto Musashi, a duelist who claimed to have never lost a match.  He is visually modeled after Hyakkimaru from the manga Dororo.
In Gamest's 1997 Heroes Collection, Haohmaru was tied with Ukyo Tachibana for 29th (out of 50) of the staff's favorite character rank. He was also voted as the second favorite character by the development team and fans in Samurai Shodown II. According to the Q&A page for Neo Geo Battle Coliseum, developers admitted that no matter what the fans wanted, they wanted to include Samurai Shodown characters and made Haohmaru's inclusion one of their top priorities in development. A "Samurai Spirits Team" was originally scheduled to participate in The King of Fighters '95 and The King of Fighters '96. This idea was eventually dropped due to time constraints. The developer notes that Haohmaru would've been on the team alongside Nakoruru and Galford. 
Garou: Mark of the Wolves planner and The King of Fighters XIV producer Yasuyuki Oda states that Haohmaru and his rival Genjuro are his favourite characters from the Samurai Shodown series. He also makes regular appearances in the series's merchandise and has at least two action figures.
At the age of fifteen, he challenged Jubei Yagyu to a duel but lost due to lack of experience. Jubei, amused by the youth's bravado, brought Haohmaru to Nicotine Caffeine so that he may gain proper training. Whilst living there, he also met and befriended Genjuro Kibagami, fellow student and another orphan like himself.
Both students were close friends, yet Genjuro's hunger for power worried Nicotine. To test his students, he tempted them to fight over the treasured sword, Fugudoku. They were tested by facing off with a group of other fighters. In contrast to his friend, Haohmaru fought only until his opponent lost the will to fight and didn't give chase. After Genjuro left Nicotine's home, Haohmaru was rewarded with the sword. Encouraged by his master to further improve himself, Haohmaru travels the lands perfecting his sword skills, and searches for worthy challengers in the name of Shura.
In Samurai Shodown V, Haohmaru challenges Yoshitora to a duel in order to test his own strength. In his ending Yoshitora accepts his challenge, asking the latter to join him and help him build a new country. Haohmaru replies that if he loses, he'll join Yoshitora. They fight but the result of their match is uncertain. 2 years later after confronting the unusual anomalies brought about by Shizuka Gozen, Haohmaru embarks on a journey to stop Amakusa from bringing Ambrosia into the mortal realm.  After killing Amakusa, Oshizu appears to him, having followed him to Shimabara. He dismisses her, telling her that he can't choose between his sword and his woman and leaves.
Not long after, he encounters Shizumaru Hisame and teaches him the philosophy of the sword at an early age. A woman named Shiori meets the wandering Haohmaru and asks him to kill the "demon".  Thanks to Haohmaru's teachings, Shizumaru slays Zankuro and avenges his parents death in the process.  Haohmaru continues his journey shortly after and runs into Genjuro in Samurai Shodown IV, the outcome of their duel is unknown.
One night, Haohmaru was suddenly attacked but easily defeated the sinister assailant. Haohmaru's attacker who was being manipulated by an evil force told him that his soul will be used for Ambrosia's resurrection.   Haohmaru, sensing an evil force rivaling Amakusa, pays a visit on his old fencing master. While Haohmaru relates his story, his master's visage grows unusually grim. He tells Haohmaru to stay away, he acknowledges how much stronger Haohmaru has gotten but forbid him from confronting the threat head on. The two share a few drinks to celebrate their reunion after a long separation, at dawn Haohmaru slips out unannounced to embark on his next journey.   At the end of Samurai Shodown II, Haohmaru defeats Mizuki and leaves the Makai gate that Nakoruru seals shortly after. 
In his ending, Genjuro approaches a wounded Haohmaru with the intention of killing him, Oshizu however runs to the wounded Haohmaru's side. She pleads Genjuro to not kill him, and instead challenge Haohmaru when he's better, this results in Genjuro sparring his life. Haohmaru embraces Oshizu and then apologizes to her, as he still wants to dedicate himself to his swordplay.
In Samurai Shodown 64, Haohmaru continues to travel the land to polish his fighting skills. However he notices a mysterious woman has been persistently tailing him. Haohmaru has no idea who she is, but he is soon reluctantly caught in the designs of the evil, dark figure who manipulates her.  It's later revealed that the mysterious puppeteer called Yuga the Destroyer, is seeking a male counterpart to Shiki and chooses Haohmaru to fulfill its requirements for a perfect resurrection. The two face each other and Haohmaru emerges victorious destroying Yuga's physical form in the process.  A year later, a brainwashed Shiki and Shadow Asura ambush Haohmaru and turn him into a cold blooded murderer also known as “Sword Demon Haohmaru”.  Together with Shadow Asura and Shiki, they defended the entrance of Yuga’s lair.
After the two Asura's killed Yuga, Shiki along with Haohmaru were finally freed from Yuga’s influence and returned to their normal states.  In Genjuro's ending, he and Haohmaru face each other once more, but this time Genjuro gains the upper hand. Before he could deal the final blow, a boy stabs him in vengeance for his unnamed father. It's heavily implied that Genjuro dies from his wound and, as promised, an older Haohmaru toasts to his friend's honor. Shiki leaves her daughter under Haohmaru and Nicotine's care as her servitude to Yuga made her feel unworthy of being a mother.
In Warriors Rage, Haohmaru is a skilled and active swordsman at the age of forty-seven who is revered by many to be the "Legendary Swordsman". He learns that his adopted niece, Mikoto, ran away from the temple (her childhood home) and follows her to the cursed island of Riten Kyo.  There, he grows aware of the evil entities at work there, and departs on a journey to stop the Razor Trio, as well as duel worthy opponents along the way. Haohmaru was also informed of a "catastrophe" that may occur on the cursed island by the holy spirit Nakoruru.  He kills Oboro and in his ending, Haohmaru eventually reaches Mikoto at Riten Kyo and reveals her unspoken past to her.
Confident in his abilities, Haohmaru enjoys the thrill of fighting against strong opponents. Seeking enlightenment with each encounter, he constantly journeys in order to improve himself while also taking it upon himself to fight against typical evil-doers. As he gets older, he feels less inclined to fight and will try to avoid it if possible.
Outside of battle, Haohmaru is a crude but easy-going man, caring only for sake and food. He has a romantic interest in a simple girl named Oshizu ("O" added as a honorific prefix).
- Hurricane Attack: He can create a small hurricane with a slash of his sword. Upon contact, the hurricane sends the enemy flying.
- Energy Slash: He can use ki energy to increase damage of his slashing attacks.
- Deflection: His jug can somehow be used to deflect projectiles of all sorts with proper timing.
Much of his fighting style revolves around power-based swordplay, and seems to be personalized by himself, focusing on wide slashes and fierce-two-handed swings, along with some occasional bare-handed brawling. He can use his sake jug to hit the opponent or to reflect projectiles. His trademark moves are Kogetsuzan (Arc Moon Slash), a crescent shaped uppercut, and Senpuu Retsu Zan (Whirlwind Rending Slash), a whirlwind projectile which can launch targets up into the air with a vertically-expanding tornado on hit. In Samurai Shodown II, he also gained a somersault slamming slash known as the Resshin Zan (Violent Quake Slash), which could cause massive damage upon crouching foes and giving him a bit of a mixup game.
Most of his special moves have the term ougi (secret skill) put before them (save for his fake Senpuu Retsu Zan, where the "gi" is the kanji for "fake/imitation" as a pun). He is also one of the few characters to sport a special move that can only be done while dashing, namely his Shippuu Kogetsu Zan (Hurricane Arc Moon Slash), which has normally possesses afterimages and more forward momentum to differentiate from its stationary counterpart.
When his style splits in Samurai Shodown III, his Slash/Shura form retains several strategies used in previous games, being a balanced and easy-to-master mid-ranged combatant. By contrast, his Bust/Rasetsu form (which becomes the basis for Rasetsumaru) alters several moves, granting him access to aggressive close-combat fighting which includes shoulder charges (his Gouha/Strong Blast), a proximity counter (Nagi Yaiba/Calm Blade) and wind splash wave that goes a small distance (Senpuu Ha/Whirlwind Wave) in the place of his feint. His appearance in Warriors Rage also combined some elements from Genjuro's fighting style such as his stance and crouching strikes.
One thing is certain, Haohmaru is a shotoclone who alters the archetype by being mainly more power-based compared to most beginner-type characters, with his infamous standing Hard Slash, the Zantetsusen (Slashing Iron Flash) being one of the series' longer-reaching and strongest attacks (even with the Zankousen/Slashing Steel Flash being an even stronger version of it). Said Hard Slash even in Capcom vs. SNK 2 deals a massive amount of hitstop on a connected hit, which even slows the frame-rate of the game down somewhat for dramatic effect. Haohmaru's gameplay himself serves as one of the primary introductions to the overall gameplay of the series (heavy-whiff punish focus with less emphasis on combos and more emphasis on hard reads).
In Soul Calibur VI however, Haohmaru not only gains a plethora of extra moves with using his latest animations as reference, but also now gains the skills of both his Shura/Slash and Rasetsu/Bust attacks (even with additions from the 64 games), and also gains his low sliding move shared with Genjuro (the Nagiashi/Calm Leg) from Sen. He also has a bare-handed stance known as Sude Kenka (Bare-Handed Brawling), a nod to his home series' ability to fight unarmed (as well as the act of deliberate self-disarming in certain titles).
- Tune of the man - Day (男節 日, Obushi - Hi) - Samurai Shodown
- Path of the man (男道, Otoko michi) - Samurai Shodown II
- Sake of the man (男酒, Otoko Zake) - Samurai Shodown III
- Path of Shura (修羅道, Shuradou) - Samurai Shodown IV, SNK vs. Capcom: The Match of the Millennium
- Zeal (精進, Shoujin) - Samurai Shodown 64
- Champion (覇者, Hasha) - Samurai Shodown 64-2
- Meeting Haohmaru (覇王丸見参, Haoumaru Kenzan) - Samurai Shodown: Warriors Rage
- Legend (伝説, Densetsu) - Samurai Shodown: Warriors Rage
- Sakura (櫻, Sakura) - Samurai Shodown V
- Supreme King Path (覇王道, Haoudou) - Samurai Shodown (2019)
- Imperial Sundance - Samurai Remix VA
- Tune of the man - Dual souls - Soulcalibur VI
Shurado is often used together with Bushido. Whereas Bushido represents discipline and moral code, Shurado represents walking a road of war and carnage without regrets. Shoujin can be translated as either zeal, devotion or concentration, and it is often used as term for advancing in quest for enlightenment. Sakura are also a common Japanese symbol used to describe the transience and beauty of life.
- Masaki Usui - Samurai Shodown ~ Samurai Shodown IV, Sen, Samurai Shodown VI (re-dub voice), Neo Geo Battle Coliseum
- Dorio Takaya - Samurai Shodown V
- Daiki Nakamura - 64 series, Warriors Rage, Samurai Shodown (2019); Capcom vs SNK 2, The King of Fighters All Star, Soulcalibur VI (Japanese voice)
- Hiroyuki Koga - Samurai Shodown VI
- Toshiyuki Morikawa - Samurai Spirits Oni
- Shingo Katori - Samurai Shodown: Motion Picture
- Milton Lawrence - Samurai Shodown: Motion Picture (English voice)
- Bin Shimada - Samurai Shodown Dengeki drama CD series
- Samurai Shodown
- Quiz King of Fighters
- Samurai Shodown II
- Samurai Shodown III
- Shinsetsu Samurai Spirits: Bushidou Retsuden
- Samurai Shodown IV
- Samurai Shodown 64
- Samurai Shodown 64-2 - his Shura/Slash form will not appear as a CPU opponent
- Samurai Shodown!
- Samurai Shodown! 2
- Samurai Shodown: Warriors Rage
- SNK vs Capcom: Match of the Millenium
- Capcom vs SNK 2
- Samurai Shodown V
- Samurai Shodown V Special
- Samurai Shodown V Perfect
- Samurai Shodown VI
- Neo Geo Battle Coliseum
- Samurai Shodown Sen
- Samurai Spirits (pachinko)
- Samurai Spirits Oni
- Samurai Spirits Kengou Hachi-ban Shoubu
- Samurai Shodown (2019) (also in Retro 3D graphics)
- Soulcalibur VI - DLC Guest character
- Days of Memories (third and seventh titles) - unplayable
- Neo Geo Tennis Coliseum
- Samurai Spirits - Shimensouka
- Samurai Spirits - Makai Rineki
- SNK Dream Battle
- SNK High School Collection
- KOF x Fatal Fury
- Granblue Fantasy
- Yamato Chronicle
- The SAMURAI KINGDOM
- If World
- Samurai Shodown Online
- Kingdom Story
- The King of Fighters '98 Ultimate Match Online
- Kimi wa Hero
- Samurai Shodown: Oborozuki Densetsu
- Samurai Shodown Tenkadaiichi Kenkakuden
- Might & Magic: Elemental Guardians
- SNK All Star
- The King of Fighters: All Star
- Dark Avenger X
- SNK Fighting Age
- Puzzle & Dragons
- SNK Gals' Fighters - cameo in background of hot springs arena, together with Jubei
- Nakoruru: Ano Hito kara no Okurimono
- Samurai Spirits Gaiden: Cham Cham
- The King of Fighters: Maximum Impact 2 - Ryo Sakazaki's Normal Outfit-Variation E
- The King of Fighters XIII - DLC background cameo (NESTS Kyo); also in the Esaka stage (in the night)
- The King of Fighters XIV - in Nakoruru vs. Chin pre-fight talk, mentioned as "sake bottle warrior", and in text-cameo in Nakoruru's win quote
- Lost Saga - as a premium character skin
- SNK Heroines: Tag Team Frenzy - in Nakoruru's ending
- Super Smash Bros. Ultimate - As a spirit
- When asked "The path of the sword is?", Haohmaru's response is "The path on which you must gamble your life and walk to the end." 
- His favourite type of mate is a Yamato nadeshiko. 
- Among all characters in the Samurai Shodown series, only Haohmaru has been ever voiced in English, from his appearance in Soul Calibur VI.
- Official character profile from Samurai Shodown anniversary website.
- SNK Playmore. "Samurai Spirits Genealogy". Samurai Shodown V.
- Shiroi, Eiji. "Fated? Rivals". Samurai Shodown.
- At the SNK heyday development scene, the creators of those days look back. Roundtable discussion for the 40th anniversary laughter Interview from denfaminicogamer.
- SNK Playmore. "Samurai Spirits Genealogy". Samurai Shodown V.
- Samurai Shodown III character profiles from the anniversary website.
- Samurai Shodown II page from Samurai Shodown anniversary website.
- Samurai Shodown 64 character profiles from the anniversary website.
- Samurai Shodown Warriors Rage character profiles from the anniversary website.