Ryu (Ryū?, written as Ryū in the original Street Fighter) is a video game character created by Capcom, the main protagonist of the Street Fighter series.

Premiering in the first Street Fighter, Ryu appears as the lead character from the game along with his best friend Ken participating in the Street Fighter tournament. Further games from the series show Ryu to be highly focused on his training, aiming to become the strongest he can. However, his powers also attract several criminals who want to use him for their plans.

Ryu has been the lead character of the Street Fighter series since the first game and has appeared in crossovers involving the franchise. He is also featured in manga from the series, anime adaptations and the 1994 live-action film.

In the first Street Fighter game, Ryu has red hair and wears a tattered white karate gi with a white hachimaki (headband) and red gloves. Also, a constant trait in his design is the Fūrinkazan kanji motif (meaning Wind, Wood, Fire, Mountain), battle standard of the historical Japanese military leader Takeda Shingen, embroidered into his obi, simulating Karate Dan degrees. In Street Fighter II Ryu is shown to be older, with brown hair and a red hachimaki. He also fights barefooted this time. The Alpha series features a Ryu much like the one depicted in the original Street Fighter, with light red hair and a white hachimaki. In the Street Fighter III games, Ryu has black hair and facial stubble to show his growth in age. Street Fighter IV, story wise, is set between Street Fighter II and Street Fighter 3 and so Ryu has a more mature look than he does in Street Fighter II but still not as aged looking as in Street Fighter 3.

Because he was the only playable character in the original Street Fighter, Ryu's designer, Manabu Takemura, wanted to make him easy to identify with. In Street Fighter II, the character was selected for inclusion due to his presence in the first game, symbolizing the concept of a Japanese martial artist. As the series progressed, the design was made more muscular to coincide with the concept, while his white gi, considered his most defining character by the development team, was meant to let viewers know he was "a karate master at first sight".

Fighting style
Both Ryu and Ken are practitioners of a nameless martial art rooted as an assassination style.Both Ryu and Ken learned their art from Gouken, who refined the style as a purely combative non-killing style. Since the SNES version of Street Fighter II, Ryu's fighting style has been referred as "Shotokan" in the English localization of the games' instruction manuals and related literature.

While Ryu and Ken follow the same martial arts discipline, as the Street Fighter series evolved, the differences between the two characters was portrayed by their attacks: Ryu focused on technique while Ken opted for stylish unpredictability. His Shōryū-ken ("Rising Dragon Fist") does only one hit, so Ryu can effectively use this move at full power against airborne opponents. Ryu focuses more on the Hadou principle of his style, which translates to him being very skilled with his usage of ki - Ryu has the most concentrated Hadōken ("Surge Fist") amongst all users. In addition, Ryu has mastered the Tatsumaki-Senpū kyaku ("Tornado Whirlwind Kick"), a powerful kick performed in mid-air. Ryu has been given special moves in various games, among those, Jōdan Sokutō Geri ("High Side Kick"), a fast side kick only available to him in the iterations of Street Fighter III.

His enhanced moves are: Shinkū Hadōken ("Vacuum Surge Fist"), a powered-up variant of his standard Hadōken, the Shinkū Tatsumaki-Senpū Kyaku ("Vacuum Tornado Whirlwind Kick"), a stationary variant of the normal move, but much faster, stronger and hitting multiple times, Shin Shōryū-ken ("True Rising Dragon Fist"), a powerful version of the standard Shōryū-ken. In addition, in Street Fighter III, Ryu masters the Denjin Hadōken (" Thunder Blade Surge Fist"), fast electrified variation of the Hadōken, which has the ability to stun the opponent. In Street Fighter IV, Ryu gains the Metsu Hadōken ( "Destructive Surge Fist"), an incredibly powerful enhanced Shinkū Hadōken, as his Ultra Combo, however, in Super Street Fighter IV, the upcoming update to Street Fighter IV, he gains the Metsu Shōryū-ken ("Destructive Rising Dragon Fist"), an incredibly powerful enhanced version of the Shin Shōryū-ken, as his second Ultra Combo.