Major Guile is a central figure in the Street Fighter series, known for his stoic demeanor and unwavering sense of justice. He holds the rank of Major in the United States Air Force, a fact that deeply informs his disciplined and strategic approach to combat. His physical appearance is iconic and deliberately crafted to embody an all-American archetype, featuring a chiseled jaw, light blue eyes, and a famously tall, blonde flattop haircut, which is maintained with a special high-grade hairspray. His muscular build is often on display, clad in a dark green tank top and camouflage pants, and he sports tattoos of the American flag on both of his arms. Around his neck, he wears not only his own dog tags but also those of his missing best friend and former commanding officer, Charlie Nash, a constant reminder of his driving purpose.

The primary motivation that defines Guile is the search for the truth behind Charlie’s disappearance and the subsequent quest for revenge. He holds the evil dictator M. Bison and his criminal organization Shadaloo directly responsible for the death of his comrade. This burning desire for vengeance is the engine that propels him into the World Warrior tournament, leading him to desert his post and, at least temporarily, his family. Beneath his calm and serious exterior lies an intense fury, which he struggles to keep in check. Despite this inner turmoil, he is a man of great loyalty, both to his country and to those he considers friends. He is a loving husband to his wife, Julia, and a devoted father to his daughter, Amy, and his internal conflict often stems from the tension between his duty as a soldier seeking justice and his responsibilities as a family man.

Guile’s role in the story has evolved over the series. He is first driven by revenge against M. Bison during the events of Street Fighter II, finally cornering his nemesis but choosing to spare him at the pleas of his wife and daughter, realizing that killing Bison would not bring back Charlie. In subsequent games like Street Fighter IV and V, his motivations shift from pure vengeance to a more measured sense of duty. He continues to investigate the remnants of Shadaloo and its new fronts, such as the S.I.N. corporation, partially because he holds onto a slim hope that Charlie might still be alive. His character development sees him mature from a man nearly consumed by hatred to a stoic mentor figure. He eventually finds a measure of peace, reconciling with the resurrected but changed Charlie, and later retires from active fighting to focus on his family and guide a new generation of fighters.

Key relationships are central to Guile’s identity. His bond with Charlie Nash is the most significant, serving as the emotional core of his character arc. He also shares a close professional respect with Interpol agent Chun-Li, often collaborating with her to dismantle Shadaloo. In a more personal connection, his wife Julia is the sister of Eliza, who is married to Ken Masters, making Guile and Ken brothers-in-law, a fact that subtly links two of the series’ most prominent American fighters. He also takes on a mentorship role with the younger fighter Abel, guiding him and working alongside him as a tag partner.

In terms of fighting ability, Guile is a master of a unique form of combat taught to him by Charlie. His technique is patient and defensive, focusing on controlling space and punishing an opponent’s mistakes. His two signature special moves have become legendary in the fighting game genre. The first is the Sonic Boom, a powerful crescent-shaped projectile fired with a swift chopping motion of his arms. The second is the Flash Kick, a powerful, lightning-fast jumping uppercut performed as a backflip, used primarily as an anti-air attack. Both of these moves require a "charge" motion, meaning the player must hold a direction for a moment before executing them, which perfectly complements Guile’s strategic, counter-attacking style. He can also perform more powerful versions of these techniques, such as the multi-hitting Sonic Hurricane and the Double Flash.