Alex - The new main character of the SF3 series who fights with close-range wrestling and quick rushing attacks. His goal is to avenge the defeat of his friend Tom at the hands of Gill.
Dudley - Voiced by Bruce Robertson in Street Fighter III and Second Impact, and by Francis Diakowsky in Third Strike. A dandy British boxer who is trying to retrieve an antique car that Gill has stolen. He is a homage to the anime series Ashita no Joe and Hajime no Ippo.
Elena - An African princess who uses the fighting style of capoeira. She seeks to make new friends.
Ibuki - An aspiring ninja whose fight in the tournament is part of her final exam. She is very quick and agile.
Necro - Voiced by Michael X. Sommers in Street Fighter III and Second Impact, and by Lawrence Bayne in Third Strike. Necro is a Russian man who was kidnapped and experimented on in the Illuminati's "G-Project". In 2nd Impact, he finds a companion named Effie who follows him and mimicks his actions
Oro - Voiced by Kan Tokumaru in Street Fighter III and Second Impact, and by Takashi Matsuyama in Third Strike. An ancient, mysterious hermit who seeks a fighter that is worthy to inherit his fighting style. He binds one arm while fighting, to keep from accidentally killing his opponent.
Sean - A young Brazilian fighter who is being trained by Ken, Sean wants to improve his skills and prove his ability.
Yang - Voiced by Koji Tobe in Street Fighter III and Second Impact, and by Masakazu Suzuki in Third Strike. Yang is a Kung Fu expert from Hong Kong, and the twin brother of Yun. Yang is identical to Yun with regards to gameplay in Street Fighter III, but gameplay differences between the two were introduced in Second Impact.
Yun - A cocky fighter who, along with Yang, protects his hometown in Hong Kong. He's a happy-go-lucky person who likes to do things his own way.
Gill (final boss. Selectable only in console versions. Although Twelve can use his Super Art X-Copy to transform into Gill when fighting against him.) - The leader of the secret organization known as the Illuminati, he wants to restore balance to the world. He can manipulate fire and ice.
Akuma (returns from Super Street Fighter II Turbo as a secret character and has a non-playable "Shin" version. Was made a regular character in 3rd Strike while his "Shin" version was removed, though in the arcade game this version is present as a near-complete character, including a recolored stage) - Continues to seek perfection through the way of the warrior.
Hugo (inspired by the Andore enemies from the Final Fight series, also a direct nod to professional wrestler André the Giant) - A professional wrestler who wants to find a strong tag team partner. He is often accompanied by his manager, Poison. He is a rival to Alex. Hugo was planned to be in the first game, as evidenced by his mobile character with unfinished sprites, and the presence of his stage in the original arcade game.
Urien - Gill's younger, bitter brother who wants to forcibly take the Illuminati from him. He can manipulate electricity and metal.
Chun-Li (returns from Street Fighter II) - She is looking for a young orphan under her care who was kidnapped under mysterious circumstances.
Makoto - Voiced by Makoto Tsumura. Makoto is a young Japanese girl, trained in Rindoukan karate. Since her father's death, Makoto's dojo has been floundering, so she finds Ryu and challenges him to restore her dojo to a flourishing state.
Q - Voiced by Len Carlson. Q is a mysterious figure, with a featureless facemask and a concealing overcoat. While he can be chosen as a playable character, he is a hidden boss as a computer-controlled opponent.
Remy - Voiced by Eiji Sekiguchi. Remy is a long-haired fighter wearing a leather jacket emblazoned with an omega (Ω). He bears a grudge against all fighters since his father disappeared and his sister died.
T.W.E.L.V.E. - T.W.E.L.V.E. is one of the first successful soldiers of the Illuminati's "G-Project" experiment, and can shape his body into weapons. T.W.E.L.V.E. is ordered to hunt down and kill his prototype, Necro, as his first mission.