The inclusion of a female character named Ran Hibiki in the Rival Schools expansion Nekketsu Seisyun Nikki 2 (Japan only, 1999) led to much speculation that she is, in fact, Dan's sister. Besides sharing the same surname the link between Rival Schools and Dan is already well established in the form of Sakura, who is both a student at Tamagawa Minami High School (in Rival Schools) and a 'student' of Dan's fighting style (in Street Fighter). It stands to reason, then, that Dan and his family exist locally to the events of the Rival Schools series, making the idea that he has a sister attending Taiyo high school at least plausible. However, the two characters do not share an obvious family likeness and as Capcom have not made any official comment the relationship is firmly in the realm of conjecture.
Intriguingly, the existence of Dan's sister is given further examination in his ending to Marvel Super Heroes Vs. Street Fighter (1997) where Dan is prevented from killing Cyber Akuma by the comedic revelation from his previously unseen sister that Cyber Akuma is their father! Unlike Ran Hibiki, however, this character bears a likeness to Dan that is humorous in its similarity. This sequence is yet another dig at SNK's Art of Fighting, it being a parody of Ryo's ending in which his sister stops him from finishing off Mr. Karate by revealing that he is their father!
Dan's family evidently provides for much speculation amongst Street Fighter fans and arguably one of the more outlandish theories holds that Donovan Baine, a dhampir and the principal character in Night Warriors: Darkstalkers' Revenge, is a distant relation of his. The basis for this claim is nothing more than the canny resemblance each character shares (notably the flick of hair projecting from the centre of their foreheads and the structure of their faces). The similarity is perhaps most pronounced with the 'chibi' style designs utilised in Super Puzzle Fighter II Turbo (pictured). Both Warriors' Dreams and Darkstalkers' Revenge were released in 1995 so it is plausible that the same initial sketches (borrowing from SNK's Robert and Ryo) were adapted for both Donovan and Dan.
Official images of Dan's father Go Hibiki are extraordinarily elusive, such that Capcom seem to be deliberately withholding a definitive portrait (for example, in Dan's IV prologue the photograph of Go on the wall is obscured by a ray of sunshine, reflecting). He does appear unobscured in the Udon Street Fighter Legends: Chun-Li comic where he closely resembles Dan, albeit with a much larger nose. In-game, Go makes a cameo appearance in the comedic off-shoot Super Gem Fighter Mini-Mix (otherwise known as Pocket Fighter) where he can be seen in several of Dan's attacks, including a parody of Akuma's Shun Goku Satsu in which the kanji 'father' is displayed (a symbol occasionally depicted on the back of Dan's gi). This version of Go, wearing a green gi and tengu mask is a parody of SNK's Art of Fighting character Mr. Karate, (father to Ryo, who was, of course, the inspiration behind Dan, bringing us full circle!) The costume worn by Go in Pocket Fighter reappears as an alternate costume set for Dan in Super IV.
Cadillac's and Dinosaurs, a 1993 Capcom arcade based on the Xenozoic Tales comics (and produced as a tie-in to the animated tv series), features a reptilian/humanoid character named Bludge who is strikingly similar to Blanka in appearance. Both characters have green skin, orange hair, ripped brown shorts and sharp claws as well as sharing a similar build and near-identical sprite when knocked down. The positive reception of the Blanka character in 1991's World Warrior almost certainly inspired this look alike, some two years after.
Entitled 'Saikyo no Corabo Meshi' (roughly, 'The Strongest Collaborative Meal') the Benitora Gyoza Bo and Wan Zhu Ji restaurant chains in China featured a special menu of Street Fighter themed meals as part of the promotion for home versions of Street Fighter IV. Exclusive trading cards were also given away with the Street Fighter inspired dishes; reportedly two for each order placed, drawn from a deck of thirty cards. Exclusive artwork was created for the promotion featuring a number of characters posing with their respective meals. Whilst the rest of the chosen cast are depicted in their default costumes, Cammy fans will be interested to see the Delta Red operative sporting a chef's uniform over the top of her traditional leotard!
Dhalsim's wife Sally makes another cameo appearance in the 'Exciting Street Scene' stage in India in Super Street Fighter IV. As per her animation in Alpha 2 and Alpha 3 she will react to the fight in progress, cheering if Dhalsim is victorious in attack. If neither combatant is Dhalsim she will remain seated against the wall selling fruit, which assumedly is a source of income for the family outside of Dhalsim's winnings.