Ambiguously Bi

So there's this person (who we will call Bob) who seems to flirt with everyone. Maybe he has a suspiciously large number of Stupid Sexy Flanders moments; or maybe he just doesn't care about the sheer amount of Ho Yay that he seems to have. They might not say so, but there is a decent chance that they might be bisexual.

NOTE: If a character has Ho Yay with their Heterosexual Life Partner and no one else it's not this trope; nor is it this trope if they get shipped with every other character. In regards to the "suspiciously large Stupid Sexy Flanders moments" if an otherwise heterosexual character repeatedly mentions that they think one particular character of the same sex is attractive it's not this trope, and is more likely If It's You It's Okay. If they say something along the lines of "I'd tap that" or makes a pass at several other people of the same sex it's probably this trope.

Compare/Contrast Ambiguously Gay, Bi the Way, and Depraved Bisexual.

Anime and Manga

 * In Zero no Tsukaima Julio is canonically in love with Louise, but may or may not also have an interest in her boyfriend Saito as shown when he tells Saito whether jokingly or not that he loves him and wants to kiss him as well as Louise. His supposed attraction to Saito is only mentioned twice though.
 * And Kirche. She is very fond of both Saito and Colbert and she seems to like Louise and Tabitha as well.
 * Gokudera of Katekyo Hitman Reborn seemingly has considerable Ho Yay towards Tsuna (though its not clear if its really love or just Undying Loyalty). He also blushed and had a nosebleed upon seeing Lal Mirch (a beautiful woman) naked.
 * Also Mukuro who has subtext with Tsuna, Hibari, and Chrome.
 * Yuujirou of Princess Princess is shown to have an interest in girls but may or may not also have feelings for Tooru.
 * Uragiri wa Boku no Namae wo Shitteiru: Luka. He's was Yuki's lover when Yuki was a girl but now also seems to still have feelings for Yuki now that he's been reincarnated as a boy.
 * A few characters in Axis Powers Hetalia are this.
 * Ayame of Fruits Basket, unless he's straight. He is in love with his adorable assistant Mine Kuramae but has no trouble flirting with Shigure. Apparently, when he was Student Council President he claimed that if needed, he'd give himself to both men and women alike.
 * Haru too, based on how he has a female Love Interest, flirts with Tohru and seems to like to hit on Yuki. He even told Tohru that Yuki was his "first love".
 * Several in Bleach:
 * Haineko seems to have a thing for flirting with and invading the personal space of both guys and girls.
 * Also, Orihime, who is in love with Ichigo but seems to really like Rukia. To say nothing of one splash page that has Orihime and Rukia very obviously naked and holding hands.
 * Tatsuki: Although she beats up Chizuru for hitting on Orihime, she's very much a Tomboy, has a very close relationship with Orihime, and in chapter 412 she thinks about how beautiful Rangiku is and thinks "Damn that Ichigo, I never heard anything about him knowing a babe like that." However, this could or could not simply be jealousy, hinting a secret attraction to Ichigo.
 * Rangiku gets a lot of Les Yay with girls, especially with Orihime, but also likes to flirt with and tease boys.
 * Lisa Yadomaru clearly has feelings for her former captain Kyoraku, but is often seen reading what seems to be porn magazines with lots of bikini-clad women on them.
 * Aizen, too. Seems to have enjoyed violating both 's and Orihime's personal space.
 * Loly as well. She seems obsessed with Aizen to a Yandere degree but also has a lot of uncomfortable Les Yay and Foe Yay with Orihime. Her interactions with Orihime make her come off as a Psycho Lesbian or a Depraved Bisexual targeting the girl she's jealous of and probably wants for herself at the same time.
 * Vincent of Pandora Hearts. He seems to like Ada but he also is obsessed with and loves his older brother Gil. What kind of love is up for debate.
 * Graham Spectre from Baccano tends to come off like this. First, there's his utterly massive man-crush on Ladd Russo. Then there's his complete disregard for the personal space for pretty much every male he comes in contact with. And then there's that thing he seems to have for Jacuzzi ("Should I let this woman go in deference to you locking up my heart?") which peaks when he waltzes up to Jacuzzi entirely unprovoked and declares, "I like you," while cocking his head as if he were about to kiss him before telling him he has free access to his warehouse and wandering off. But he also expresses some interest in Chane, and claims that he likes older woman. Not to mention that he supposedly has a thing for his own sister. Of course, he's a total nut, so who knows.
 * Fullmetal Alchemist: Sig Curtis might be bisexual. He loves his wife, no question about it, but his "flex-off" with Major Armstrong which ends with the two of them holding hands and sparkling makes ya wonder.
 * In Higurashi no Naku Koro ni Rena and Shion are ambiguously bi. Rena takes home anyone regardless of their gender, age, or species. Shion has a considerable amount of Incest Subtext with her twin sister, despite having a canon male love interest.
 * Koizumi Itsuki from Haruhi Suzumiya seems to like invading the main male character's personal space a little too much in the Anime, and in the novels especially he makes it quite clear that he trusts and likes Kyon. He claims to act the way he does because Haruhi expects it and would make it real if he didn't, which would be a plausible explanation if he actually did do so while Haruhi is watching. Also, in the 4th novel, but this isn't brought up in the main storyline - although many of his actions and words towards Haruhi, especially his constant claiming of being "the expert of her heart" imply some secret affection for her. Whatever the case may be, Itsuki's bond with Kyon could be seen as a fumbled attempt at a bromance or an actual romance slowly developing.
 * The titular Haruhi Suzumiya. She makes it very clear right from the start that she doesn't care about the gender of the one she is with, as long as he or she is not an ordinary human being. She doesn't seem to have been dating girls though, but perhaps that was simply because only guys confessed to her. Also, she seems to like Kyon and also likes to Skinship Grope Mikuru (whether its out of genuine interest or not remains to be seen).
 * In Code Geass, Lelouch, as if he weren't busy enough, finds himself in the center of a Love Dodecahedron that is too complex to get into here, but suffice it to say, he's apparently been romantically linked in-universe to most of the female student body of Ashford Academy, as well as at least two of his own sisters, but also has strong feelings toward Suzaku and Rolo. Of course, he thought Rolo was his brother and Suzaku's been a close friend since early childhood, but the series never fully resolves that.
 * Also, Milly is hinted to have feelings for both Shirley and Lelouch.
 * In Rosario to Vampire, young Yukari announces to her classmates that she's fallen in love with both Moka and Tsukune, but it's not clear if she herself fully understands the implications of that statement.
 * D.N.Angel: Satoshi Hiwatari. It's hinted that he may have feelings for Risa. In the anime, it is also hinted that Satoshi may have romantic feelings for Daisuke. When this is brought up, he doesn't openly confess to anything, though he never denies the accusations either. If anything, he encourages the idea, which has led to the source of much confusion regarding his motives. It has even been stated outright by Dark that Daisuke is the one who causes Satoshi to turn into Krad. Krad himself has also hinted at Satoshi possibly wanting more than a friendship from Daisuke at least once in the anime, and more than twice in the manga. In any case, he at least wants to be close to Daisuke despite the danger of Krad to both of them.
 * Lavi of D.Gray-man. He goes nuts whenever he sees a pretty girl but he also seemingly has considerable Ho Yay towards Allen and Kanda.
 * Viscount Druitt of Black Butler. He takes a liking to the maid Hannah and plenty of pretty ladies but also appears to flirt with Ciel both when he's Disguised in Drag and when he's dressed normally as a boy.
 * Sebastian. To the fans he is either this, or Ambiguously Gay,but he did have sex with Matilda and it is heavily implied that he did the same with Beast. He also has a ton of Ho Yay with Ciel and other males.
 * Ippo Makunouchi of Hajime no Ippo. He's got a quite sweet crush on Kumi Mashiba and she more or less reciprocates, but his attitude towards his very handsome rival Ichiro Miyata is so tinted with Ho Yay that his friends don't hesitate to say he's "gay for Miyata". And there's his also very good-looking Russian friend Volg, too...
 * Minto from Tokyo Mew Mew has a hero-worship for Zakuro that definitely verges into Les Yay at times (she even confesses her love at one point, though in context it's ambiguous what kind of love she was talking about), but also shows interest in guys and when Ichigo asked the other Mews what they considered attractive, she pictured a male dancer.
 * Death Note drops strong hints that Matsuda is this, if not just outright gay - though he does seem attracted to Sayu in the second half of the series. He is known to be quite "fond" of Light, following him in a manner that could easily be indicative of a crush. He shows no jealously whatsoever when seeing Light with women, but this may just be him accepting that Light is straight and would of course have no interest in him. His actions near the end as he shoots Light and screams at him almost look like the reaction of a lover learning the truth about his significant other. And then there's his throwing an arm around a blushing male coworker...
 * Sayu certainly qualifies as well. Her interest seems to be primarily in women; she happily flips through the Porn Stash she finds in her brother's room, states that Misa is "her type", and says she has no interest in dating men. However, she also mentions having a crush on a male celebrity.
 * Also, L. He's definitely sexually attracted to Misa (even though he finds her stupid and annoying) but he has enough Ho Yay with Light to power a small village. Of course, L also has No Social Skills so his tendency to stare creepily at/ obsess over men and women might just be him being weird...
 * Hinako of Goshuushou Sama Ninomiya Kun. On the one hand she seems to like, whether jokingly or not, to flirt with and harass Shungo but also appears to like to Skinship Grope Mayu (whether or not its out of genuine interest or because Mayu is a succubus is never made clear).
 * Griffith of Berserk, at least before the Eclipse where he became a Complete Monster who probably doesn't concern himself with sexuality or romance anymore. Even though we know that Griffith, he might very well have had some unrequited feelings for both Guts and Casca, judging from the fact that a) he was a complete Yandere when it came to Guts, through and through, b) before activating his crimson behelit a la Despair Event Horizon, Griffith did have a vision of   and to top it off, c) he gave Guts and Casca the Kubrick Stare when it was evident that they had become a couple.
 * Angel Sanctuary's Rosiel. No Sense of Personal Space in a Cast Full of Pretty Boys? Yes. Combine with the outfits and dilute with No Sex Allowed In Heaven? Oh yes.
 * A lot of characters in Revolutionary Girl Utena are Ambiguously Bi like Utena herself, Wakaba, and Akio as well as others.
 * Yuuri and Sara in Kyo Kara Maoh.
 * Sheryl Nome of Macross Frontier, definitely into guys, takes a seemingly random interest in Ranka when they first meet (and stares at her QUITE a bit), and makes an off-hand remark about Nanase's voluptuousness (which Nanase then calls her out to stop staring at her with those "lecherous eyes"). Oh, and did we mention she french kisses herself? She has a habit of creating multiple holographic versions of herself on stage in the movies, which she uses to accomplish that. The second movie takes this one step further with the holographic Other-Sheryl appearing to be a guy. In short, she may have just somehow combined this trope with Narcissism.
 * Also, the one guy she has an interest in suffers from Dude Looks Like a Lady.
 * Suruga of Bakemonogatari. Despite declaring herself a lesbian, she seems to have a number of lewd ideas involving Koyomi.
 * In Angel Beats, Hinata often tells Otonashi he likes him (it's used as a joke, maybe). Later, he tells Yui he likes her and would marry her if they met when they were still alive.

Comics

 * Hercules was implied to have had relations with a large number of women and Northstar.
 * Deadpool comes from the "flirts with everybody" and the "suspiciously large number of Stupid Sexy Flanders moments" schools of ambiguous bisexuality.
 * Wonder Woman, with more or less subtlety Depending on the Writer.
 * Black Canary, especially under Gail Simone's pen. At one point she was going to quip that she was "75% heterosexual" thus making her Bi the Way, but placeholder dialog confusion turned it into "heterosexual to the bone." There's also the fact that when she believes she's going to have to fight a Duel to the Death she tells Huntress to tell both Barbara and Oliver Queen, her ex-husband, that she loves them. In that order. To say nothing of this.

Film

 * Jay from the View Askewniverse hits on practically every woman he sees and loudly proclaims that he likes women. He has also (in a roundabout fashion) admitted to thinking about men when he touched himself.
 * LeFou of Beauty and the Beast is a little too into Gaston but was also drooling over the Bimbettes a split second before they "accidentally" sprayed him with water.
 * Janis Ian in Mean Girls is definitely ambiguously bi.
 * Jack Sparrow of Pirates of the Caribbean. He's shown on screen to be interested in woman and Johnny Depp (the actor who plays him) has said that he's bisexual (not that the concept really existed during that time period, so Jack himself would be unlikely to identify that way), and has considerable Ho Yay / Foe Yay with other male characters.
 * Megamind: Megamind: Yes, he did  but what about those scenes with Metro Man when it turned out   Smelled all rather Ho Yay, or maybe Foe Yay-ish, to some. Or that criminally tight spandex suit and his fascination with leather? And his guy-liner?

Literature

 * Harry Dresden from the The Dresden Files is definitely this. Though he can be quite chauvanistic and has a lot of male gaze and has dated several women in the story, he also shows a lot of attraction to men. He often remarks how Greek God like Thomas is, and pretends to be his boyfriend at one point to break into his flat. He regularly notices the muscles on his friend Michael, on the werewolf Billy while he is NAKED and various other Knights of the Cross. He also has a LOT of sexual tension with Mob Boss Marcone. There is a reason they're possibly the most popular pairing in the books. Harry describes repeatedly Marcone's eyes, Marcone sends goons to follow and protect him, keeps trying to get Harry to work for him, and despite Harry's very balck and white morality, he can't bring himself to hate Marcone.
 * In The Long Walk, McVries seems to care about Garraty in a way that extends beyond friendship. He's also mentioned to have had a girlfriend.
 * Carlisle (especially movie continuity Carlisle) of Twilight is more than a little of this. He's an extremely well-dressed (look at that coordinated shirt and tie in the hospital scene! That extremely sexy shade of blue!) has an immaculately clean and artistically decorated house, loves to cook (if only because, as a vampire, he doesn't get to very often) and has a lot of "foster kids" but none of his own. He's also a ridiculously pale, ridiculously blond bishonen. He also has a wife. He's also just a few years older than his "children" are supposed to be. You cannot tell me that if you saw him and Edward in a public place together your first thought would be that they were father and son. In fact, when Eddie's mom told him to save him, Carlisle changed Edward with the intentions of the two of them being companions. The flashback in the movie where he turns Edward is ridiculously full of subtext. In the books Edward mentions Carlisle spent a lot of time in Italy a few centuries back, where he hung out with a load of male vampires who were models for works of art. He left after he got sick of them trying to "convert him to their lifestyle" it wasn't just blood Edward meant.
 * Eragon from Inheritance Cycle comes off as this, though his obsession with an unattainable elf girl indicates that he's straight. Despite this, he travels and becomes EXTREMELY close to his half-brother Murtagh, and starts getting vengeful and sulky when Murtagh turns out to think he's an annoying little twerp. Additionally he never notices Arya's sexual characteristics (read: breasts), but he spends a lot of time ogling his master's muscles, "port-red lips" and long, flowing hair, and starts staring intently at the guy's "hairless groin" during a naked bath scene. He also ogles the "hard and lean" muscles of his crippled ex-nemesis, and even drops his pants (but not underwear) in front of his cousin to show a very intimately-placed bruise.

Live Action TV

 * Hawkeye Pierce from MASH has flirted with everybody except for Sherman Potter. Admittedly, he was just doing it to be a Jerkass half the time, but there are ways of doing that that don't make people question your sexual preferences.
 * Dean from Supernatural proclaims that he likes women, but he has a ton of Ho Yay with Castiel and other males and has been known to check out other guys. He also becomes nearly breathless in the presence of Dr. Sexy M.D.
 * Ambiguously bisexual seems to be a trend: Crowley, Bobby (he used tongue) and Gabriel all show signs of swinging both ways.
 * Pretty much every demon or angel from Supernatural can be seen as at least ambiguously bi, given their predilection for genderswapping their meatsuits/vessels. Take Meg when she possessed Sam and went after Jo, or Lucifer appearing in both male and female forms to essentially seduce his vessels. Although the entire concept of gender is pretty ambiguous for angels especially, making the question of sexuality even more confusing.
 * Amy Farra Fowler from The Big Bang Theory makes constant remarks on how sexy her (female) bestie is, but will still vie for the affections of men and Sheldon.
 * Sam Evans from Glee is...not gay. But he shows an odd amount of interest in his fellow athlete's bodies flicks Finn's nipple after a erotic comment from Santana, shows no discomfort with Camp Gay Kurt, and wishes he had a relationship with Artie like the one their (lesbian lover) girlfriends have. If the rumors are true about Sam, he was originally hired on and written as Kurt's boyfriend, but then put aside when they got Darren Criss on the show - but a lot of his dialogue remained the same and they kept the character on for a season to see if they could get him to gel as a heterosexual (he didn't). As a result, the character comes off as ridiculously bisexual.
 * Karen Walker on Will and Grace. Married to men several times, has had many male partners, but, well, That Other Wiki has a whole section on her page about her sexuality.
 * The Dean from Community starts out as this in the first season, then into the realm of clearly disturbed individual, skipping canonical altogether.
 * Shawn, Gus, and Lassiter of Psych have all had homoerotic moments, usually played for laughs, and Shawn far more than the other two.
 * Gregory House is attracted to Cuddy and has slept with female prostitutes, but also has a lot of Ho Yay with other males. In particular he's hinted to like Wilson a lot, and Hugh Laurie has agreed with the statement that Wilson is "the other love of [House's] life."
 * Penelope Taynt of The Amanda Show. She's utterly obsessed with Amanda (both Amanda and Penelope are played by Amanda Bynes) and once had a thing with a guy who was just as obsessed with Amanda as she was.

Stand-Up
""I'm 41, maybe I'll do the second half gay. It remains an option. There's gotta be something to it, because those people are having a good time: they have parades!""
 * Louis CK, in one of his routines, mentions that he saw a beautiful couple; a beautiful woman together with a beautiful man. He then says that he doesn't care that the man is beautiful and that he'd be willing to suck his dick.

Video Games

 * Pete Kowalski and Vance Medici of Bully.
 * In .hack//G.U. we have Endrance.

Visual Novels

 * Saber of Fate/stay night has her main relationship with the male Shirou, but she also doesn't mind Rin getting involved, and in the end of the Unlimited Blades Work ending actually becomes part of Rin's harem along with Shirou. There's also the fact that in Fate/Zero her relationship with Iryasviel is more than a little eyebrow-raising, though it never appears to go past the Courtly Love level.

Western Animation

 * Both Shego and the titular character of Kim Possible are Ambiguously Bi. They show considerable amounts of Foe Yay and Les Yay toward each other, one episode has their 'friendship' overshadowing Kim and her own boyfriend's relationship (his reaction doesn't help either), and they have had either male love interests or show attraction to men.
 * Double D of Ed, Edd 'n' Eddy. He was shown to go all Love Makes You Dumb over Nazz like most of the other boys in the neighborhood, and some scenes between Double D and Eddy in The Movie just scream Unresolved Sexual Tension. (Plus Eddy's brother thought Double D was a girl and came to the conclusion that Double D was Eddy's "girlfriend") Also, in the episode 'Key to My Ed', Ed is dancing around while Rolf's playing music. He grabs Eddy and slams him into Double D, the two catching each other in a dancing position. Double D's only remark is a smirk and, "What? No flowers?" Also, his only complaint of Ed trying to kiss him under the mistletoe was that someone might be watching.
 * Jimmy was already Ambiguously Gay to begin with, appears to exhibit gay tendencies towards other guys, and has a crush on Sarah.
 * Homer in The Simpsons. He's Happily Married to Marge and he's also hugged and kissed his neighbor Ned and filmed him naked in the shower, on several occasions commented how attractive another man was, and is the Trope Namer for Stupid Sexy Flanders. He's also been kissed by another man on two separate occasions, and while clearly surprised didn't react negatively either. Also, in one episode Homer and Chief Wiggum develop a friendship that verges on Ho Yay at times and in the episode "Donnie Fatso", Homer teams up with the FBI to infiltrate the mob, and becomes incredibly close to Fat Tony. True, the constant touching, hugging, and kisses on the cheek could be Handwaved by Tony being an Italian gentleman, but when Tony dies of a heart attack during a sting, Homer mourns like he just lost the love of his life. It's rather sweet, and a tad suspect. He also flirts hopelessly with a "sensitive but rugged" manatee lover, completely failing to understand why Marge isn't in love with him.
 * Ralph Wiggum too. He once referred Bart as his boyfriend and upon seeing Bart naked in the movie said "I like men now!" Another time he hugs Comic Books Guy and says he will never let go. He also has interest in Lisa.
 * Peter in Family Guy. He's married to Lois and has shown attraction to females but we also have the episode where Peter starts hanging out with Bill Clinton. The two hit it off right away, but Peter spends so much time with the guy that he ends up damaging his relationship with Lois. By the end of the episode both of them have been physically seduced by Clinton as well. The last scene? We get a shot of Peter laying next to Clinton in bed. It should also be noted that Peter had a very shocked look on his face while Clinton had a very satisfied look on his face. Peter then states: "Boy you are good. You are really good." Also, Meg likes boys but is also hinted to have a Psycho Lesbian attraction to Connie, and Lois is married to Peter but has hinted to have had lesbian experiences in the past.
 * Courtney Gripling of As Told by Ginger. She canonically likes boys but is also hinted to have Les Yay towards Ginger, at the very least she's quite fond of her.
 * The titular Tom and Jerry are sometimes shown to be after girls or have girlfriends but also seem to have a considerable amount of Foe Yay / Ho Yay with each other.
 * Slade of Teen Titans based a lot of uncomfortable subtext he has with Robin, Terra, and Raven.
 * Starfire too. She is very fond of Raven but also seems to be in love with Robin.
 * Ren Hoek as depicted in Ren and Stimpy: Adult Cartoon Party. He clearly loves the ladies and will try to grab a woman's breast at any given opportunity; yet at the same time he appears in a homosexual relationship with Stimpy, with whom he already shared an Ambiguously Gay relationship with in the original. He of course denies that he loves Stimpy and insists that they're friends.
 * SpongeBob SquarePants is said to be asexual by the creator but he still is implied to have a crush on both Sandy and Squidward.
 * Avatar: The Last Airbender: Azula has tons of Les Yay with Ty Lee and Mai and she freaks out  but she also has subtext with her brother as well trying and failing to seduce a guy at a party. Actually, she generates Foe Yay with everyone.

Webcomics
"Noah: You are surprised I have a girlfriend?
 * Ménage à 3 does this a lot: Didi, Sandra, Sonya and Gary (all supposedly straight), as well as Yuki (supposedly a lesbian) all doubt whether they might be bisexual at some point. Didi and Sandra even go as far as to try and have lesbian sex with each other, only to conclude that they're really 'two naked straight girls with poor boundary issues'. For Yuki and Sonya, the question is still in the air.
 * Belkar of Order of the Stick kissed the gender-ambiguous Vaarsuvius during a New Year's party and seems to love hitting on Roy, especially when Roy is temporarily turned into a woman and Belkar hits on "her" knowing full well who it really is.
 * Noah of El Goonish Shive. He is well aware of this.

Elliot: I ASSUMED NOTHING!

Noah: (grinning) Of course not."


 * From Homestuck, Though in this case, it's not a question of bi or straight, but rather gay or bi:
 * On the other hand, is very probably bi, but there's enough ambiguity that it's not impossible that they're really straight.