M. Bison is the primary antagonist of the Street Fighter series and the absolute ruler of the international crime syndicate known as Shadaloo. Very little is known about his past, including his true nationality and the meaning of the "M." in his name, which contributes to his mysterious and ominous presence. He is a dictator who rules his empire with an iron fist, and his ultimate ambition is nothing less than complete global domination.

Bison is the embodiment of pure, unrepentant evil. He is a ruthless, callous, and supremely arrogant megalomaniac who sees all other people, including his most loyal followers, as nothing more than pawns or tools to be used and discarded for his benefit. He has no capacity for compassion or mercy, and he destroys anyone who opposes him without hesitation. Bison's ego is vast; he considers himself to be a god among men and takes a sadistic pleasure in tormenting and oppressing others for his own selfish urges. A key insight into his character is that to gain mastery over his dark power, he deliberately purged all the goodness from his own soul. This discarded goodness later manifested as a separate entity, a woman named Rose, who is destined to oppose him.

Bison is driven by an insatiable lust for power and a desire to conquer the world. His criminal organization, Shadaloo, engages in every possible form of illegal activity, including drug trafficking, arms dealing, terrorism, and illegal human experimentation, all to fuel his ambitions and increase his influence. A recurring personal motivation is his search for a more powerful, more durable body. The immense energy of his Psycho Power constantly strains and deteriorates his physical form, forcing him to seek out new vessels to house his soul. He has shown a particular interest in taking over the body of the powerful martial artist Ryu, whose potential he sees as a perfect container for his essence.

Within the overarching story, M. Bison serves as the central source of conflict and the final obstacle for many of the series' heroes. He is the sponsor of the World Warrior tournaments, using them as a means to lure powerful fighters, generate negative energy, and eliminate his enemies. His actions have created numerous personal vendettas against him. He murdered Chun-Li's father, prompting her to become an Interpol officer seeking revenge. He also killed the friend and partner of the U.S. Air Force officer Guile, turning Guile into one of his most relentless enemies. Furthermore, he is responsible for the creation of Cammy, a genetically engineered young woman designed to be the perfect vessel for his soul and a brainwashed assassin in his elite Doll unit.

M. Bison's character shows a distinct pattern of death and rebirth throughout the series. While he is seemingly destroyed on several occasions, his powerful soul is able to survive and eventually be transferred into a new, cloned body prepared by his Shadaloo scientists. This continuous cycle of resurrection underscores his nature as a persistent, almost supernatural evil that refuses to be permanently vanquished. Despite his multiple defeats, he remains a constant threat, always plotting his return to power.

The source of Bison's immense power is Psycho Power, an inherently evil and chaotic energy that manifests as a dark purple flame. His mastery of this ability grants him superhuman strength and a wide array of devastating techniques. His most famous moves include the Psycho Crusher, where he launches himself across the screen like a spinning projectile engulfed in energy; the Double Knee Press, a diving, somersaulting kick; and the Head Press, where he teleports above his opponent and stomps down on them. Beyond these physical attacks, his Psycho Power allows him to perform feats such as teleportation, flight, and generating a limited number of illusionary duplicates of himself in battle. This combination of a ruthless personality, megalomaniacal ambition, and reality-defying dark power cements M. Bison as one of the most iconic and formidable villains in fighting game history.