Due to the vagueness (or, more accurately, inaccessibility) of Street Fighter's storylines, as well as incorrect facts/mistranslations printed in game manuals, the Street Fighter series has quite a lot of fanon material that is taken as canon by many.
- The fighting style of Ryu and Ken that has been passed down to them by Gouken has never been named in the Japanese versions of the games. A lot of Street Fighter fans outside Japan have misinterpreted the term ansatsuken (literally "assassination fist") as the name of their art. However, ansatsuken is actually a common Japanese term in fiction and in fact, Gen's unrelated fighting style has also been referred as an ansatsuken as well in the series. The fighting style of Ryu and Ken is not an ansatsuken itself, but the three special techniques they use (the Hadoken, Shoryuken, and Tatsumaki Senpukyaku) were originally part of the assassination art that Gouken and Gouki learned from Goutetsu before Gouken refined them into non-lethal, purely defensive techniques. Capcom USA's localization staff hasn't been helping matters either, often referring to Ryu and Ken's style "Ansatsuken" in source material (ignoring its use of the word as a general term).
- That the character Akuma is a demon, or at least a generally evil character; in fact, he is more of a Blood Knight. Demon is more of a description of how he fights (not to mention the literal translation of his name).
- Have Kim Kaphwan fight Akuma in one of the Capcom vs. SNK games and you'll see that Kim, who has a strong sense of justice and can simply look at an opponent to tell if he's evil or not, does not use his "Evil is unforgivable" intro with Akuma, which he does for just about any bad guy. However, in Capcom vs. SNK 2 he uses the "Aku wa yurusan...!" quote against Akuma and his Shin form, but in SNK vs. Capcom: SVC Chaos he does not. In the end, Akuma has murderous intent by giving in to the Satsui no Hadou and has likely killed before. To Kim Kaphwan, Akuma would technically be "evil" because he is a murderer, not because he is inherently evil.
- Akuma's whole goal (other than to turn Ryu to the "Dark Side") is to find powerful martial artists to fight and kill. He is literally a serial killer. He also killed his brother (well, sort of) and his sensei — though the latter happened in the context of a Duel to the Death rather than on a mere whim. He may have killed Bison, but most recent revelations tell us that probably it didn't quite happen like that: according to Street Fighter IV and its tie-in OVA, Akuma did attempt to use the Shin Goku Satsu on Bison, but Bison beat him to the punch by killing himself first. However...
- It should also be said that while Akuma has killed or attempted to kill several martial artists over the course of the series, he's not a mass murderer who roams aimlessly killing anyone he crosses paths with and will call off of the fight against his challengers if he believes they're either not ready to face him or at a disadvantage; this is why he spared Gen, who was dying of leukemia, in Alpha 2. Earlier sources also state that he merely knocked away Ken — who discovered Gouken's body almost immediately after his final duel with Akuma and then hounded Akuma — instead of killing him. Overall, Akuma adheres to a very strange honor code as a warrior and went after Bison in II because he thought Bison was misusing his power. On top of this, Akuma is not above petting the dog, as he even (circa Alpha) saved a boy who wandered into his cave and subsequently bought goods from him. One could argue that labels such as "good" and "evil" don't apply to Akuma and that he is only "evil" in the antagonistic sense (just ask Ryu), not the moral one. Of course, Character Exaggeration in crossovers and other adaptations often throw this out of the window and strip Akuma of any complexity he has under the Obviously Evil surface, furthering any misconceptions.
- In line with the above "Akuma is a demon" interpretation, some fans use his Dub Name Change from Gouki to Akuma to indicate Akuma discarding his past identity as a result of giving himself over to the Satsui no Hado in his pursuit of martial arts perfection. This also has the effect of preserving the Family Theme Naming between him and Gouken* while sidestepping the question of why their parents would name their secondborn after either an evil spirit in Japanese folkore or, worse, the Devil/Satan (or Mara from Buddhism, who is at least a little more complex by God of Evil standards). note
- Another fairly popular one is the idea that Charlie got turned into Shadow in canon itself, just like in the Marvel vs. Capcom series. Even the most recent comic books used this idea. One could even argue that this has been ascended with his return and overhauled moveset in Street Fighter V, or at least inspired Charlie's in-game depiction as a much darker and somber character.
- Before the release of Street Fighter Alpha, it was a popular bit of fanon that Charlie got turned into Blanka. This actually made it into the movie and cartoon, but that's an Alternate Universe.
- There's the theory that Street Fighter EX is an AU retelling of Street Fighter Alpha and/or Street Fighter II, which could hold true due to the inclusion of certain characters, their visual appearances and storyline motivations (for instance, Guile as opposed to Charlie, Sagat as a member of Shadaloo, and Chun-Li in her qipao instead of her Alpha-era unitard), and many of the Alpha voice cast reprising their roles in these games. There's also a ton of incorrect and simply made-up "facts" about the EX series' storyline (due to bad ports and most supplemental material staying in Japan), all of which can be viewed here.
- Several characters are given first and last names (originating from the live-action movie and American cartoon). Ryu and Chun-Li's surnames are Hoshi and Xiang/Zhang respectively, Sagat's first name (Victor), and Guile's full name and rank (Colonel William F. Guile). Dhalsim is considered his last name since he was referred to as Dr. Dhalsim in the movie.
- There's the belief that Ken defeated Ryu during the events of SFII. This one is a bit more understandable: During their last battle (in Alpha 2), Ryu was too hung up on his previous fight with Akuma and the Satsui no Hadou raging within him to focus, allowing Ken to best him quite easily. After giving Ryu a pep talk and bequeathing his hairband to his buddy (which would become Ryu's trademark red headband in all appearances chronologically following Alpha 3), Ken vows that he won't marry his then-girlfriend Eliza until he defeats Ryu again in a fair, decisive match. By the time of III, Ken and Eliza are shown to be married and have a young son named Mel, whereas IV (set roughly one year after II) depicts Eliza's pregnancy in full.
- It's accepted by many that Mike from SFI and Balrog (M. Bison in Japan) are the same fighter, but Capcom can't confirm this for legal reasons (i.e. the character being an expy of Mike Tyson). Capcom's official verdict is that they were always meant to be two separate characters from the beginning (and, in fact, lists them separately in both the Street Fighter World Warrior Encyclopedia and the Shadaloo C.R.I. character profiles for Street Fighter V), though this did not stop them from giving Balrog a costume in V based on Mike.
- Somewhat related to the above, there was a longstanding and widely accepted belief that the two nameless fighters seen in the intro to the original Street Fighter II (and its pre-Super revisions) were Mike and Joe from SFI. Even after Capcom Jossed this idea in the Street Fighter V era by revealing these two characters to be unrelated fighters by the names of Max and Scott, many fans refused to accept this as canon.
- Because the final scene of Asura's Wrath reveals the events of the game to have taken place 870 million years prior to the Street Fighter series (or at least some version of that universe), many fans assume the officially non-canon Lost Episodes are part of SF lore and use their Vs. series-style exaggerations of character ability when discussing how the various fighters measure up to one another. (ex. "If Cody is deemed to be a worthy challenge by Oni, who can fight evenly with Asura, does this mean Cody can take on Asura?")
