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.
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 D. Weller. 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.
He also makes regular appearances in the series' merchandise and has at least two action figures.
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) - Samurai Shodown
- Path of the man (
男道) - Samurai Shodown II
- Sake of the man (
男酒) - Samurai Shodown III
- Path of Shura (
修羅道) - Samurai Shodown IV, SNK vs. Capcom: The Match of the Millennium
- Zeal (
精進) - Samurai Shodown 64
- Champion (
覇者) - Samurai Shodown 64-2
- Meeting Haohmaru (
覇王丸 見参) - Samurai Shodown: Warriors Rage
- Legend (
伝説) - Samurai Shodown: Warriors Rage
- Sakura (
櫻) - Samurai Shodown V
- Way of the Overlord (
覇王の 道) - Samurai Shodown (2019)
- Imperial Sundance (インペリアルサンダンス) - 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)
- Edward Bosco - Soulcalibur VI (English voice)
- Bin Shimada - Samurai Shodown Dengeki drama CD 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.
- Haohmaru is also often accredited to defeating most of the series' villains.
- 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.
- 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.
- 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.
- Official character profile from Samurai Shodown anniversary website.
- 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.