In most series, either Everyone Is Bi or there are No Bisexuals; there's usually not much room in between. However, there is one group of bisexuals who seem all too well represented in the mainstream: the cold-blooded murderous sociopaths.
This is a very different phenomenon from the Psycho Lesbian trope. Whereas the Psycho Lesbian is usually violent or deranged out of unrequited love and/or jealousy, the typical Depraved Bisexual is bi because, well, why not? Their willingness to sleep with everyone they can is just one facet of their being Ax-Crazy. A slightly less pathological version of the trope depicts the Depraved Bisexual as "simply" supremely manipulative; recognizing the effectiveness of sex as a control mechanism, they resort to it at every opportunity - reasoning that successful seductions gain new thralls, while even unsuccessful ones tend to increase others' fear of you. Male instances are disproportionately likely to be Sissy Villains, but not as often as you might think.
Interestingly enough, though, many if not most Lesbian Vampires are in fact bisexual. Fanservice, you know.
More common in film than on TV, where queerfolk of any sort, and especially bisexuals, were a rarity until recently. Of the TV instances, several are Mirror Universeduplicates, to show just how evil and different they are from the originals. At one time this was practically the only way an explicitly bisexual character could appear in any film, anywhere; in his book Bisexual Characters in Film, Wayne Bryant is able to fill a whole chapter of examples of this, as well as another book about bisexual murder victims. In more pleasant examples, bisexual characters simply don't follow Cast Speciation as much as a solidly gay character does and are less likely to be used. An exception is in a mystery plot, where a potential ex-lover being a suspect suddenly becomes much harder to pin down.
Contrast Bi the Way, where the character just happens to be attracted to men and women without being so... extreme; and Anything That Moves, where the bisexual/pansexual character just happens to be alsohypersexual.
It goes without saying that in Real Life the majority of bisexual persons (and, at least according to Alfred Kinsey, most people have some level of both same-sex and opposite-sex attraction) are notAx-Crazy. That plus the potential for Flame Bait means there will be no Real Life examples.
There's a good number of Depraved Bisexuals in Texhnolyze.
They don't get any more depraved and handsome than Dr. Kazutaka Muraki from Yami No Matsuei.
Although whether he's 'just' being supremely manipulative and hypersexual, or it's just all part of one great squirming Scalpel Crazy package, kind of fluctuates depending on where you are in the plot and whether it's the anime or manga because... the writer is unreliable. About everything. Seriously.
Grell Sutcliff from Black Butler, though she's more pansexual than anything. She's is a chainsaw-wielding, male-to-female TranssexualDark Action Girl that is very forward about her attraction to Sebastian, within the same five minutes talking about both wanting to cut him into pieces and being the mother of his child. Her affections are not just limited to Sebastian; in general, she loves to flirt with anyone that takes her fancy. For example, with William Spears and the Undertaker, she seems enamored by their pretty eyes. She also initially fell in love with Madame Red and later killed her, and once commented that she thought Alois's Ninja Maid Hannah Anafeloz had a cute/pretty face — before stabbing her.
At one point in the 8th novel, Haruhi also wrestled Kyon and stripped him of his blazer. The grappling techniques she used were mount◊ and guard◊. Kyon thought "Is stripping Asahina-san not enough for you, you perverted girl!?" and called it "reverse sexual harassment". It leads to a classic Not What It Looks Likescene◊.
In the novels she once actually reached up Mikuru's skirt before Kyon intervened.
Ryoufu Housen from Ikki Tousen is pretty close to this during the first season. Though her Schoolgirl Lesbians relationship with her best friend Chinkyuu humanizes her, she also has sex with her leader Toutaku and her ex-boyfriend Saji for power play reasons, and either rapes (anime) or gropes (manga) her rival Ryoumou Shimei.
Griffith, from Berserk, defines this trope. He'd be the object of a lot more yaoi pairings if it weren't for the fact that he betrayed the entire Band of the Hawk, killed everyone except Guts and Casca, and raped Casca while he forced Guts to watch. There's no changing that.
He mostly seems to be of the manipulative variety, seeing as he only had sex in order to take advantage of someone.
Then again, that's what makes Griffith so.... ambiguous. Even though we know that Griffith screwed Princess Charlotte just to make himself feel better after Guts left, he might very well have 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 he and Casca sharing a quiet, peaceful life together, child and all and to top it off, c) he gave Guts and Casca the Kubrick Stare when it was evident that they had become a couple. So one can see how being a Green-Eyed Monster for two people made Griffith become a monster during the Eclipse.
Akio Ohtori, the villain from Revolutionary Girl Utena, uses sex as a tool for manipulation, seducing boys and girls, including his own sister, alike for his own ends. Touga seems to have picked up his book of tricks as well, using the protagonist, his male Unlucky Childhood Friend, and everyone else to get what he wants.
The Dorok emperor from Nausicaä of the Valley of the Wind, who makes advances towards both Kushana and Yupa, and probably has the fewest redeeming qualities of any character in the entire series - or its author's entire body of work, for that matter.
And very possibly Yui. For a while, her behavior towards Miaka and Tamahome was rather obsessive and she acted like something akin to a Yandere in regards to both of them.
The Emperor of Kutou also counts. In the anime he is shown raping Nakago as a child and also had more than one wife/concubine.
Tomomi Harukawa from Moonlight Lady is this trope: she practically drags the protagonist Suzuna and her young cousin Io into the sack (never at the same time). This is partially due to her innate affection for them both, and a strange spell that removes her inhibitions
Gauron from Full Metal Panic! is. Kalinin describes him as "dissolute and given up to hedonism", which is a nice way of saying "depraved" or "lax in morals". There are implications that his relationship with the twins Yu Fan and Yu Lan are not limited to the normal father-daughter kind: Being raised by him, they are shown to be rather knowledgeable at how to seduce men, they "wipe his body down," and are completely devastated when they learn that he doesn't have much longer to live; they willingly undertake a suicide mission at his behest rather than outlive him, and are shown to be completely devoid of happiness, save for what little they can gain from being reunited with their Sensei despite the circumstances. On the other hand, he canonically is obsessively in love with Sousuke (in his own twisted way), to the point where he was unable to forget about "beautiful" 12-year-old Sousuke since their first meeting five years ago. And if the implications of that weren't depraved enough, he also exhibits necrophiliac tendencies, having apparently fantasized fucking Sousuke's corpse after killing him.
In the novels, he once had a thing with a female scientist and strangled her on one occasion. They both seemed to get off on it, as Gauron even lampshades it by mocking her, asking her if she actually likes making him angry, and actually wants him to hurt her. He says this with a perfect mixture of "coldness and joy," and she responds by gasping with "pain and ecstasy."
In the novels, being the sick pervert he is, he shows interest in humiliating and possibly molesting/raping Tessa (to "break" her spirit, since he's annoyed with "righteous" people). He makes it very clear to the other submarine personnel that if they try to do anything, he ''will' do "X-rated" things to the cute captain. When she acts defiant towards him, it "pleased him from the bottom of his heart," and he exclaims, "Ohhh, she's cute!" and proceeds to jokingly ask the Mithril traitors if they're sure they want to leave, since this place seems like a nice place to work.
Jouji "George" Koizumi from Paradise Kiss is extremely debatable. It depends on whether you see him as a Jerk with a Heart of Gold, or a plain old self-centered, vain Jerk Ass with no heart whatsoever. Either way, he's openly bisexual, very kinky, and very vocal about his love of bondage. Even though it's never implied his bisexuality is related in any way to it, he's clearly fucked in the head and has a ton of issues.
Shira from manga/Blade of the Immortal. He doesn't care what gender his victims are, so long as he can get his kicks from them. And unfortunately, his fantasies are really perverted, twisted, and violent (raping people while he cuts them up). In earlier chapters, he outright explains that he always needs someone to keep "the part down there" happy, and then when his arm is cut off and he can no longer visit brothels he kidnaps a young boy (Renzo), forces him to take care of him, and rapes him.
Sakura Gari: A big reason why Souma is depicted as being messed up and depraved is because he sleeps with women and men (ignoring later implications that he causes their death).
Also, Katsuragi, who not only is a disgusting pedophile, he rapes and tortures Masataka because of his jealousy over Masataka being the one Souma loves when he loves Souma to an insane degree himself and he beats his wife. Oh, and when he was younger he also persuaded Souma into wanting to kill his mother and when Souma couldn't go through with it he took Souma's hand (that held a knife) and forcibly made him cut his mother's wrists. And he also raped Souma when he was still a child as well.
Genma from the second season of Darker Than Black is one of these, and is an utterly loathsome psychopath, despite his seemingly affable and bumbling manner (and oddly enough, he's partner with a more sympathetic Psycho Lesbian). Genma's primary interest seems to be for young boys, but he makes perverted comments implying that he's open to anything. He also has a highly sadistic streak and reveals casually that he was the one who killed his perky human partner, Yoko, and she was clearly tortured to death.
Hisoka from Hunter × Hunter. If he's not killing someone, he's usually hitting on the main (mostly male) characters, including the 12-year-old protagonists. He doesn't limit himself to shota boys, though. He's also got the hots for Kuroro and Machi.
Possibly Osanai from Paprika. He's obsessed with Chiba and shares a bed with the Chairman; there's also an off-hand mention that he "sold his body" to Himuro.
Hinako takes this Up to Eleven in Episode 8 when she strips and forces Mayu into a swimsuit and apron while cooking ramen. Irori subsequently walks in on them and then the two of them force her into one too. Later when Shinobu shows up, the three of them force her into one as well and at this point they're all doing with way more gusto than required. To top it off just before Shungo returns home with ingredients for the ramen, they've been thinking certain thoughts about how big and hard that wooden spoon they're stirring the ramen with is. And they certainly don't spare many details on the individual stripping of each girl.
Wolf Guy - Wolfen Crest has Haguro Dou, the young son of a powerful Yakuza boss, and who becomes completely and crazily obsessed with protagonist (and werewolf) Inugami. He initially doesn't care about or even think twice about Inugami... until he pushes Inugami too far. Which results in Inugami showing him his true form and scaring the shit out of Haguro. Haguro goes insane from it, and obsesses and stalks Inugami after that, even cutting himself all over his arm and carving the word "Inu" onto his hand. And yes, it's creepy to the point of being something of a sexual obsession as well - Haguro has been shown after that to, while having sex with his (equally crazy) girlfriend (who, by the way, also lusts after Inugami and thinks about him while having sex with Haguro), think only about Inugami, and screams his name while imagining him. And later Haguro decides to up his freakiness by beating up his subordinate Chiba, kissing him, taking the opportunity to tear out his tongue, and then rape him. All because Chiba happened to run into Inugami in the street earlier and talked to him when Haguro wasn't around. And he also tortures and rapes a female teacher named Aoshika (who's in love with Inugamiand is the guy's Morality Chain) while recording it so that Inugami can see, practically talking to the camera (and, therefore, to Inugami) through the entire thing so that Inugami will come back to him. He also tries to kill Aoshika while telling her that Inugami's too good for her and when Inugami shows up to stop him, Haguro cuts off Inugami's fingers and eats them (even getting a boner from doing so) and an arm and tries to murder him.
Possibly the Phantom from MÄR. He falls in love with Alma and seems to have an obsession with his enemy Alviss. He even tries to kiss Alviss twice, licks the tears off his face, and there's an arc in the anime dedicated to him kidnapping Alviss, brainwashing him, and keeping him chained to his throne.
Masao Kirishima from Mars is an effeminate sociopath who was often bullied by his only friend, Yuji Aoki. Rei had saved Masao from being beaten to death at one point in time, but barely remembers this event as the action was impulsively taken when Rei was still in shock over Sei's death. Soon after this incident, Masao kills Aoki. While Masao admits to having a crush on Rei, he also says that he has a crush on Kira, who he sees as an obstacle in getting to Rei. His personality and mind is very much twisted, and he stalks and attempts to kill both Rei and Kira in the series.
Swordfish from the yaoi manga Under Grand Hotel. As one inmate put it, "he's just a crazy bisexual homophobe that likes guys" and is obsessed with Sen.
Tatsuha Uesugi of Gravitation. He's bisexual and is completely and utterly obsessed with Ryuichi. Whether it's faking illnesses or dressing up in an animal suit, Tatsuha will do anything to get Ryuichi. Unfortunately for Shuichi, if Tatsuha can't get his hands on Ryuichi he forces his UST upon Shuichi as Shuichi resembles Ryuichi (An example of this was shown in the anime, when Tatshua sexually molested and thrust himself upon Shuichi before Yuki appeared).
Issei of Ookami Kakushi. He stalks and tries to molest Hiroshi a few times and right before dying kisses a girl who had a crush on him.
Possibly Bryan Hawk of Hajime No Ippo. He only cares about sex and violence. If he can't get enough violence, he needs sex to compensate for it. It's also implied that he gets sexually aroused from beating up his opponents (or at least Takamura).
Bible Black: Kitami at the start. Most of the cast when they come under Kitami's sway.
Shinra from They Are My Noble Masters, has no qualms about sexually harassing, and in a few instances, raping Miyu. Miyu...doesn't seem to fight her off real hard. Miyu and Shinra are sisters. Yeah, its that kind of show.
Sayonara, Zetsubou-Sensei: Subverted by Nozomu. It's shown in Zan that for the sake of the principle of being open-minded, he had a one night stand with a butch blonde transsexual gigolo (who looked like an unshaven twin of GTO in a dress) in a love hotel...and hated it (he was filled with despair while they were doing it).
Head from Star Driver is a classic Type 2, seeing sex as just another tool for manipulation.
Also, Madoka Kei is willing to go for anyone, and is prepared to use some rather... disturbing methods to accomplish it.
Debatable with Ritsu Minami in Loveless. He loved Soubi's mother and was furious when she married another man, and seemed to have no problem sexually abusing her son Soubi in her place. It could also be that, like many real life child sexual abusers, his abuse of Soubi had more to do with control than actual physical attraction.
Lio Shirazumi from Kara no Kyoukai. Possibly. He not only lusts after Shiki, but seems to feel this way about Mikiya as well.
Also implied with Revy as of chapter 81 (either this or Situational Sexuality), where she essentially threatens to make Jane her bitch by saying that when she was in prison she was so good that her partners could never go back to anyone else. Given that it's Revy it's hard to tell if this is real or an invocation of this trope as a threat.
In Gamaran, Masato Nikaido: to sum things up, he's a large man who wears a kimono usually worn by women, along with earrings and nail polish, enjoys killing and maiming in a creepy way both men and girls and when a young Shinnojo managed to wound him he grew obsessed with him. Finally, as a pun, he uses two swords, and in Japanese slang, the term "Manto" (two/both blades) designate bisexuals.
Anri of Adekan is a prime example - terribly psychotic, and his bisexuality is self-confessed (and demonstrated - he seduces a man and a woman within the space of a few panels.
"It's true! I love men and women!"
Tsukiyama Shuu from Tokyo Ghoul. He mentions having been quite taken with Touka when they were younger, and becomes Kaneki's Stalker with a Crush as the series progresses. Most of his interest is about eating the people he finds attractive, and as a result he is responsible for quite a bit of the Interplay of Sex and Violence in the series.
Wolverine's son (yes, son) Daken is apparently one of these; he has a long-term girlfriend, but he seduces a man just so he can kill him and take his passport. And now that's taken on his father's mantle in the Dark Wolverine series, Daken appears determined to sleep his way through the Dark Avengers team. It helps that he has sex-pollen pheromone powers that effect everybody differently. Venom/Mac Gargan has "strange feelings" for Daken. Hawkeye/Bullseye get royally cheesed off at him etc. Oddly, Word of God states that Daken is actually asexual. He treats sex as nothing but a tool to manipulate people.
Since it was a replica with everything intentionally Up to Eleven, created by a (likely fairly conservative) gypsy sorceress Margali Szardos, this isn't entirely surprising. The way it's presented also implies that the disturbing part is the depraved sleaziness than the bisexual.
Also from X-Men we have Mystique, who subverts this trope. While she is undoubtedly a villain, her relationships with Destiny and others are used to humanize her.
Ennis also uses this trope in Preacher with T.C., Jesus De Sade, Starr, and others (the first two being depraved omnisexuals).
Poison Ivy and Harley Quinn, the former frequently using Mind Control pheromones as a weapon against both men and women, the latter almost as love-crazed for Ivy as for The Joker, with the sexual component of their relationship, having received frequent hints even in the animated series, canon in main universe of the comic books. Though the latter is also something of a subversion. Generally their time together is portrayed quite positively, when they aren't committing crimes anyway, and shows Harley taking just a bit of independence from Mista' J.
Batman villain Jane Doe is implied to be this in Arkham Asylum: Living Hell: when she is pretending to be Anne Carver, she looks (unsuccessfully) to find men to date like how Anne would, and talked of licking caviar off the thighs of college girls instead of Warren. Her sexuality might vary depending on whoever's life she's trying to steal.
Lois in Love And Rockets. Not as evil as many of the examples here, given the Slice of Life nature of the canon, but definitely depraved and unsympathetic.
In Van Hamme and Rosinski's fantasy comic Thorgal, one of Thorgal's worst enemies, Kriss de Valnor, appears to be bisexual after quite a long time, as she openly flirts with Aaricia, and grabs her breasts, while taking a bath with her in the absence of Thorgal.
Junior of Secret Six mentions having "forced relations" with both women and men. Plus Junior's Freudian Excuse of being sexually abused by her father, Ragdoll Sr., which caused her to mutilate her own body to its current state. This is almost certainly not supposed to reflect negatively on bisexuals, since the team contains another anti-heroic lesbian Scandal and the bisexual Jeanette, and at least one as-of-yet unrevealed male member of the Six is bi per Word of God.
Jade is given this characterization in Victorious fanfic Glorious, due to her relationship with a now Futa!Cat Valentine being put into jeopardy by Tori. Jade's first decision is to take control by getting incriminating evidence of Tori, then confronts Tori in the janitor's closet to intimidate and blackmail her.
Margaret in Liquid Sky - she knows that everyone who has sex with her dies, so she makes it a habit of seducing anyone she wants to get rid of, some of whom are total Jerkasses, regardless of their gender. As such it's not entirely certain if she even counts as truly bisexual since she may not be attracted to any of them.
Buffalo Bill from Silence of the Lambs, although it's quite likely that he isn't a real bisexual, but just wants to fit in somewhere. He's certainly not a transsexual, something Hannibal explicitly points out.
Credence Leonore Gielgud from Troll 2, who breaks into a house just to deliver a poisoned cake and hit on the family's teenage daughter, then has sex with with the girl's boyfriend's friend (with the help of a corn cob).
Adrien Brody's character in Oxygen, a kidnapper whose brawny accomplice, "Handsome", is a guy he seduced into working with him.
Repo! The Genetic Opera has Pavi Largo, a bisexual rapist who likes to cut off women's faces and attach them to his own with surgical staples.
The eponymous "Ivy" from Poison Ivy, who seduces The Ingenue, then her father, then starts killing people.
Conway Twill in Dead Man on fellow hitman Cole Wilson: "Fucked his parents. Mother. Father. Parents. Both of 'em. Fucked 'em." And then he ate them. It's implied that Twill himself meets a similar fate, although possibly without the fucking.
It's implied that Serial Killer David Allen Griffin from The Watcher is this. When the hero, Joel, is discussing his motive, he says that he revives his (always female) victims over and over again to torment them, and there's a shot of one of his victims bleeding from between her legs. On the flip side, however, Griffin has a lot of Ho Yay with Joel, to the point where he'll murder Joel's girlfriends if they distract Joel from chasing him.
Possibly Rainbow Randolph from the film Death to Smoochy. He rants very vulgarly about his past relationship with female protagonist Nora Wells, but the Foe Yay with Sheldon(Smoochy) is hard to ignore. And, y'know, Rainbow Randolph.
That certainly puts the lyric "Friends come in all sizes" in a new light.
That song was a whole string of Double Entendre: "Some like to pitch and others to catch", anyone?
As mentioned below, Dorian Gray is an ambiguous example, but the 2009 film version makes this rather explicit; though he definitely leans toward women, he also sexually interacts with a few men. And, well, the depravedpart...
Taken to the most extreme possible extent in British horror movie Mum & Dad.
The title character of Jennifers Body, though it's more like Depraved Succubus
Van Helsing: The Brides of Dracula display some additional lesbian tendencies, especially Brides Verona and Aleera.
Dracula himself. He shows interest in making Anna his bride, and a lot of his dialogue and actions towards Van Helsing seem pretty flirtatious considering Van Helsing is the one who originally killed him.
The character Tim De Laatste Zomer (The Last Summer) is a more milder example.
Samantha James of Just Friends. She's a damn near psychotic Yandere for Chris, says she likes girls, and kisses Darla.
La Tenia, the rapist in Irreversible. He randomly decides to rape a woman who walks past him. In another scene, he's at a gay club and smiles at the sight of a man brutally beaten to death with a fire extinguisher.
Raoul Silva, the villain in the 2012 James Bond film Skyfallmight be this: he had a relationship with one of his henchwomen and he also starts hitting on Bond... but in the latter case it isn't clear if he's being genuine or just trying to intimidate Bond (it doesn't work).
Hamidou in Midnight Express. Has two sons and attempts to rape the protagonist in the climax. Bilingual Bonus: he openly shouts in Turkish what he's going to do to poor Billy.
Vince, the Colin Firth character in Where The Truth Lies.
Lolita (1997). When Humbert confronts fellow pedophile Clare Quilty, the latter says, "I like little girls...and their fathers."
In Cormac Mccarthy's Blood Meridian there is judge Holden, who is among other things a Con Man whose Establishing Character Moment is fooling a mob into murdering a priest for crimes he made up on the fly. Later he tries his hand as scalp hunter and is also a pedophile rapist whose victims include boys and girls alike. The ending of the book implies that he might not even be human.
In Peter F. Hamilton's Night's Dawn trilogy, there is exactly one bisexual: the satanic cult member/anti-Christ/messiah of the coming apocalypse, Quinn Dexter, whose sexual depravity is constantly shown as being one of the most important facets of his character. He murders, tortures, rapes and mind rapes almost everyone he comes across and opens millions to possession by the spirits of the dead. In the third book we finally meet the person who turned him into who he is now... a depraved hermaphrodite. There may be one or two gay characters in the novels, but none of them stick out in this editor's mind...
Jonathan Randall in the Outlander book series, by virtue of being an equal opportunity sadistic rapist who, as confirmed by Word of God, only prefers men because they break better. The author is extremely careful to make this clear in the Outlandish Companion guidebook, and seems somewhat disturbed that people take his depravity and bisexuality as being directly related.
Both used and subverted in Larry Niven and Steven Barnes's book Dream Park. There are three confirmed bisexual characters, all male. One is a blackmailer who becomes a murder victim, the second is the blackmail victim and murderer, and the third is a perfectly well-adjusted guy who attempts to seduce practically the entire cast, but is always portrayed as nothing less than a perfect gentleman.
The titular character in Rebecca is implied to be bisexual.
The necromancer-villain of Deborah Turner Harris's Mages of Garillon series, Borthen Berigeld, almost certainly physically as well as morally seduced a secondary antagonist character Mage-Inquisitor Earlis ap Eadric into his service; though it's never explicitly confirmed, the character's behaviour - even to the point of turning upon Berigeld when he sees the necromancer later bedding a woman - is note-perfectly that of a mesmerized and then betrayed lover.
Characters in Bret Easton Ellis novels. A huge number of his characters are casually bisexual males from different ends of the spectrum, and a almost all of his characters are completely morally depraved and shallow. This is most notable in The Informers where every male would appear to be a shallow, blonde, Californian bisexual boytoy who is possibly a vampire. However, some notable exceptions are Paul in The Rules of Attraction, Clay in Less Than Zero and Victor in Glamorama - all different sorts of bisexuals, and flawed as characters in several ways, but ultimately the heroes of their stories in their shallow little universe.
Admiral Ges Vorrutyer in Lois Bujold's Shards of Honor is a textbook example, along with Prince Serg, his superior and lover.
And Aral Vorkosigan is a subversion.
As is Bel Thorne, though in its case it was a hermaphrodite to start with.
Cersei is a possible example. She uses sex to manipulate men, and has an affair with a woman with whom she conspires. In her affair with the woman, however, it's not completely clear who is manipulating whom, and after their first sexual encounter she didn't want it to happen again, nor has she shown an attraction to any other woman.
An unusual example, as Cersei has Single-Target Sexuality for her brother Jaime, and anyone else (man or woman) that she sleeps with is for purely manipulative reasons, or to (unsatisfactorily) try to fill the void if Jaime is absent.
In-universe, Oberyn Martell is viewed as one by most of the other nobles of Westeros — he has a lot of bastards (so many that they've even got a nickname — the "Sand Snakes"), is often said to have sex with men, and is not looked on favorably for his crippling of the heir to Highgarden at a tourney years ago and his penchant for fighting with poisoned weapons. Also because his long-term paramour—basically his wife, except they're not married—is a bastard daughter, which makes her a completely unfit consort in the eyes of the rest of Westeros for even a lowly Knight, let alone the younger brother of one of the great lords. His genuinely loves his children though, and his own people don't seem to mind his sexual appetites. Compared to Gregor Clegane, though, Oberyn looks like a Knight in Shining Armor. Then again, everyone in the series looks good compared to Gregor Clegane.
By the time of A Dance With Dragons, Daenerys Targaryen has recieved the reputation of Depraved Omnisexual in Volantis and Slaver's Bay, courtesy of the many wild-running rumors about her.
Ramsay Snow, the "Bastard of Bolton". It's strongly implied that he rapes women regularly, but his relationship with "Reek" is filled with nightmarish sexual undertones. Ultimately, he just likes to rape people regardless of gender.
The villain of Joan D. Vinge's Psion.
Max Aue from Jonathan Littell's The Kindly Ones is a homicidal sociopath. As an added bonus, his preferences are the result of his obsessive love/lust for his twin sister.
Freddy Krueger: "Come to daddy, Peter... * starts licking Peter's face and rubbing it with his bleeding stump of a hand*
Jennesta from Stan Nicholls' Orcs is a tyrannical half-human, half-Nyadd queen who gets her rocks off on raping both men and women of any species. It isn't purely for her sexual gratification, however - after she's finished with them, she proceeds to brutally murder them almost immediately, before devouring their hearts to replenish her magic.
In S.L. Viehl's Star Doc series, Rico in Shockball is the most obvious example.
Mitsuko in Jun'ichiro Tanizaki's novel Manji (or Quicksand), a chilling sexual Chessmaster despite her tender age. With the help of a small-time ruffian (which she also sleeps with), she plays victim and manipulates the emotions of housewife Sonoko, and then, having also seduced Sonoko's husband, drives the couple into reciprocal suspicion. She reaps the benefit of their emotional wreckage, gains total control over their sex life, plus their adoration befitting a goddess.
Peter Quint in Henry James's novella The Turn of the Screw is usually interpreted as such, and a pedophile to boot — but that depends on how you take the veiled hints and Victorian euphemisms. Benjamin Britten's operatic adaptation makes things slightly more explicit, especially with the sensual call-and-response duet between Quint and Miles at the end of Act 1.
Every now and then she would be staring in my face, in the chariot, and squeezing my hand, and saying, Why, you are very pretty, my silent dear! And once she offered to kiss me. But I said, I don't like this sort of carriage, Mrs. Jewkes; it is not like two persons of one sex. She fell a laughing very confidently, and said, That's prettily said, I vow! Then thou hadst rather be kissed by the other sex? 'Ifackins, I commend thee for that!
Melisande Shahrizai, of Jacqueline Carey's Kushiel's Legacy series. She is utterly evil and sadistic. Then again, everyone in Terre D'Ange is bi, so there was bound to be some evil people thrown in the mix. Aversions: Phedre, Alcuin, and Delaunay.
A lot of the Raiths. They're happy to do whatever gives them sex power. At one point, Lara flirts with both Harry and Luccio in the same scene.
Lampshaded in A Song For Nero by Tom Holt. As Nero (on the run after faking his death in the Year of the Four Emperors) says, "When you're emperor of the known world, people expect things! You can't just say 'no, i'd rather sit down and read a book' when they bring on the Libyan eunuchs crawling around on all fours in tigerskins!"
In S. M. Stirling's Shadowspawn series the entire titular race is this.
Elphaba from Wicked may count. She's a Villain Protagonist, though whether she's "evil" or not is a major point in the series. She's had a sexual relationship with a man where she conceived a son but also is confirmed to have more than platonic feelings with her friend Glinda.
Orson Scott Card's Songmaster includes a major character named Josif who is introduced as homosexual, enters a heterosexual relationship with the statement that he is '60% attracted to men, 38% attracted to women, and 2% attracted to sheep,' and ends his sexual career unable to control his urges toward a barely pubescent child, making him at least a homosexual hebephile. No meaningful counterexamples exist in the setting, in part because most of the book centers around pederasty.
Patrick Hocksetter of IT. He fondles the girls in his class, masturbates Henry and offers him oral sex.
Luce Daggett, the villain of Colleen McCullough's Indecent Obsession. His backstory is as a gigolo who serviced both men and women regardless of his own preferences, and is used as an example of his manipulative nature, but his bisexuality is also genuine and shown as part of his evil in itself, as he's an omnivorous sexual threat. His explanation to the heroine of why he's hitting on her when he hit on another man a few days ago is "young, old, male, female - it's all meat to me", which causes her to react with "revulsion" and tell him that he's damned. His final confrontation against Michael is also charged with sexual violence. In contrast, the homosexual characters in the book are portrayed as ranging from good to saintly.
Prince Bayard in The Chronicles of Magravandias. He kills without a care and is known to torture, beat, and rape people for not giving him what he wants. His lovers can't even be mentioned in polite company half the time.
From the Honor Harrington novella Let's Dance!, the commander of the Casimir depot, Edytá Sokolowska, is said to be into both physical and psychological torture of her "toys", including the threat of the prepubescent children of said "toys" being given to the station's XO, Julian Watanabe, who is no less of a torturer, if given more to the physical kind.
Malkar Gennadion AKA a lot of other things) is both the most prominent bisexual in Doctrine of Labyrinths as well its Big Bad. Aside from sex (invariably sadistic, manipulative, or both) with both men and women, he satisfies the "depraved" requirement by committing rape, Mind Rape, kidnapping, torture, and gruesome murder For the Evulz. Simon, although a less significant character, averts the trope— he's "janus" and a basically decent person.
In PS: Your Cat Is Dead, Jimmy sees Vito as this initially. Crazy Carmine actually turns out to be depraved, however, or at least refuses to take 'no' for an answer until forced to.
Russian assassin/terrorist Nadya Malovo from Robert K. Tanenbaum's Butch Karp & Marlene Ciampi legal thriller novels. She actually prefers women over men, but she'll use her seductions on anyone in order to manipulate them.
Heavily implied with Rodrick Rand, the deranged movie star in the comic neo-noir Get Blank. I mean, sure he wanted to hunt a couple people, but did he really need them in a bikini and a banana hammock?
Nicolas Bullen in The Kingdom of Little Wounds, who if he isn't attracted to men, he's willing to act like it if it gets him a step up the ladder. And then when that man dies, he's willing to act like that man's ten-year-old daughter attracts him instead.
In The Age of Innocence, Count Olenski, Ellen Olenska's husband, is implied to be this when a snide comment implies that his copious infidelities included men as well as women.
Live Action TV
Isobel from The Vampire Diaries is heavily implied to be one. She keeps a sex slave of each sex. Moreover, both are mind-controlled. The male is actually gay, and would presumably be repulsed if he were not mind-controlled, making this all the more Squicky.
Quite a few of the vampires in this show have shown an interest in sex with both genders (at one point during the third season, before Erik Northman has sex with Russel Edgington's male lover, he remarks that it's been a long time since he indulged in it "with a vampire", and both Pam and Nan Flanigan have both been shown having intimate moments with other women). The notable exception to this is Bill, who has only ever had eyes for Sookie.
Season 3 of Nip/Tuck: The Carver victimized both men and women. Also, the person behind the White Mask of Doom, Quentin Costa, had some intimate encounters as himself with a couple of female characters and a male patient.
Star Trek: A possible Alternative Character Interpretation of Captain James T. Kirk, in relation to the non-stop Ho Yay slash shipping between him and Spock - while Kirk and Spock have many moments where they appear to be more than "just friends" this doesn't stop Kirk from hooking up with just about any woman who doesn't run away from him, nor does it erase the fact that Kirk had at least one genuinely meaningful relationship with a woman, Carol Marcus (as seen in Star Trek II: The Wrath of Khan).
The character originally hit on her regular counterpart only because she was so highly narcissistic. Only later was the character made a Depraved Bisexual, with the actress herself being well aware of the Unfortunate Implications.
Joss has mentioned in interviews that they knew that either Willow or Xander would be gay/bi, but weren't sure which, hence the several subtle hints for both in the first 3 seasons.
It is notable though that Joss Whedon has explained Angel and Spike's canon sexual encounter with "they're vampires". Darla and Drusilla are strongly implied to have had a lesbian relationship and Vamp Xander in the Mirror Universe episode also lasciviously touches a male victim at one point. The implication is that vampires don't particularly care about gender when approaching sex objects, which ties into this trope quite nicely.
Mandy in 24 to an extent. There was real no connection between her depravity and her bisexual nature, and she appeared to genuinely love her girlfriend. On the other hand, both of the male lovers she had, one of whom was also bi, she killed herself.
Smallville: Non-straight people come one of two ways: this (in the form of some vampires and a woman at a fight club that is attracted to Lois) or the rare female Stalker with a Crush for Lana (the female part is rare, not the stalker/crush part. Not by a very long shot).
Given her scenes with Clark, Lana, Oliver, and Lois, Tess Mercer is probably an example, although this might just be fan interpretation.
The Carver, an arc villain from Nip/Tuck. But his wanglessness could have more to do with his depravity.
Oz is practically overflowing with these characters, seeing as how it is about a prison that houses some of the most heinous criminals imaginable. The worst of which would be homicidal sociopath Chris Keller and homicidal psychopath Simon Adebisi. Also, Tobias Beecher. He had a wife who committed suicide and he falls in love with another woman while in Oz and falls in love with Chris Keller. He also has sexual relations with several men while in Oz and shows Ax-Crazy tendencies the longer he's in Oz as well, such as when he killed a prison guard with long fingernails.
Bobbi Stakowski from Profit is a prime example of the "manipulative" subtype; when her very rich, very married boyfriend turns out to come with a pre-nup stating that the first partner to ask for a divorce forfeits all the couple's assets, she goes out and seduces his wife.
In Saul Of The Mole Men, Saul's hated rival Nathaniel Baltimore, Old-Fashioned Bisexual. Nathaniel is really just a jackass, pointlessly firing his gun while Saul is talking just to interrupt him and never once admitting that Saul was right about the Mother Rock.
Nathaniel definitely counts as depraved. He's constantly licking his lips and sizing up the asses of both Saul and Fallopia, and at one point he jumps in the middle of one of their kisses.
In Prison Break, the Magnificent Bastard villain T-Bag is another example of the really bad kind. He's not just a rapist and a murderer. He's a child rapist and a murderer.
Cy the Cyclops from Kröd Mändoon and the Flaming Sword of Fire is an openly bisexual Monster. While he seems pleasant at first, he then turns out to be utterly depraved and shows a desire to "sex and devour" the entire lead cast.
The victim of one episode of Cold Case was a stockbroker who slept with both his young male protege (who had a crush on him) and the protege's mother solely in order to get them to invest money, which he then stole. Needless to say, this was the motive for his murder.
Averted in the "Vampire Weekend" episode of Castle. Crow is weird, yes since he's part of a sexual vampire cult, but he's the victim, not the villain of the episode.
Andrew Van De Kamp on Desperate Housewives came out as gay to his parents but tells a priest he "likes vanilla, but sometimes likes chocolate." He was also a sociopath who made his mother's life a living hell, until his sociopath tendencies dissipated in Season 3, and so did any trace of his bisexualidentity.
"Mr." Yang from Psych is allegedly trying to seduce a female orderly.
Tony from the first series of Skins. While he gives his gay friend Maxxie fellatio on a school trip, it was "to try something new"; his college headmaster also refers to him as "polysexual". Up to the finale of season 1, he manipulates everyone around him, but he reaches Moral Event Horizon when after his girlfriend Michelle hooks up with another guy, Josh, he sends her pornographic pictures of Josh's sister from his phone to convince her he's mentally unstable. This fails, since Michelle still doesn't take him back, and Josh ends up enacting a truly twisted plan of revenge on him involving his sister.
Not that overt, but Bennett in Dollhouse is implied to be bisexual, or at least lesbian for Caroline during their college days. The depraved part comes when she starts torturing Echo in response to Caroline apparently abandoning her with a disabled arm.
Lee Garner, Jr., the overprivileged and idle head of North American Tobacco (the makers of Lucky Strike) in Mad Men, who has hit on both men and women to exercise his naked power and humiliate his business partners. Even at Sterling Cooper, he was powerful enough to get Sal Romano fired for rejecting his advances. After the action moves to Sterling Cooper Draper Pryce, Lucky Strike makes up (at one point) 79% of SCDP's revenue, and so when Garner says he'll be attending the company Christmas Party—intially something of a joke, as Lane wanted to run it on a shoestring budget to save money needed for other things—SCDP is forced to put on a full-on party with music, a bartender, a fully-stocked bar, and decorations up the wazoo. Garner shows up incredibly late and starts hitting on Roger Sterling's wife (never mind that their marriage isn't a good one, it's still insulting), and forces Roger to play Santa. Since Lucky Strike is 79% of the budget:
Roger Sterling: If Lee Garner wants three wise men flown in from Jerusalem, he gets it.
(Miss) H. G. Wells in Warehouse 13 is bisexual ("Many of my lovers have been men."), and depraved ( she tried to destroy all of humanity), but the two are not related, so there you are.
Although she's not violent about it, Amy Farrah Fowler from The Big Bang Theory is desperate. To the point of gleefully squealing at the possibility that she, Penny, and Bernadette might be rolling around in the mud naked together. She is also constantly hitting on Penny and shows attraction to Pruiya (Raj's sister)...and constantly tries to bribe or trick Sheldon into sleeping with her. Much to Sheldon's dismay, although he seems to be getting used to it.
Clarice Willow on Caprica is in a group marriage with both men and women, and also sets out to seduce Amanda Graystone in order to gain access to her house and later because she starts to attach a religious significance to her. It is demonstrated repeatedly that Clarice sees all of her spouses, and indeed everyone else, as tools in her quest to advance herself and her religion (in that order). Her spouses are also the members of a particularly intimate terrorist cell with her as the de facto leader. Even most of Clarice's spouses are taken aback when Clarice appears to be trying to seduce a teenage girl, and enlists her youngest husband to assist with this. Interestingly, this trope is further emphasized by the fact that the other adult characters, even the dysfunctional Graystone's, are more committed to their monogamous relationships. Most notable is the aversion of the Depraved Homosexual trope with Sam Adama, who is depicted as extremely loyal and devoted to his husband Larry.
Alby from Big Love. Although initially presented as a closeted homosexual, he stalks Bill's daughter Sarah and clearly has no problems lusting after his co-conspirator wife. His evilness, however, appears to have nothing to do with his sexuality.
PC on NYC Prep, although his sexuality is more of a sidenote to the fact that he is a manipulative, cocky asshole.
On Supernatural, the demon and later King of Hell Crowley's introduction sees him buying the soul of a middle-aged businessman, then coercing the man into a kiss to seal the deal.
He later does the same with Bobby Singer, with photographic evidence, even.
During a negotiation with Crowley, Season 7 Big Bad Dick Roman seems already aware of this little tradition.
Crowley: You have a deal. I suppose you want it in writing?
Roman: I don't kiss on the mouth.
Crowley: Your loss.
Crowley has also been known to flirt with both Sam Winchester and Castiel on occasion.
It's hinted at that Crowley and female angel Naomi once had a thing.
Crowley: (to Naomi) If you remember our time in Mesopotamia the way I do, you know I'm a lover, not a fighter.
Xander Feng's first scene in House of Cards features him being alternately serviced by a man and a woman, while he's tied up and asphyxiated.
Lost Girl The Morrigan is certainly depraved, and is bisexual. How aggressive/violent she is with her partners is unclear, but Lauren certainly didn't mind. In fact she used it to her advantage. To the show's credit, the heroine Bo is openly bisexual and is a very positive portrayal of bisexuals.
Older Than Feudalism: The ancient Greek myth of Zephyrus, who was married to his sister, but was madly in love with the young Spartan Hyacinth. However, Apollo also loved Hyacinth, and when he chose Apollo over Zephyrus, Zephyrus went crazy and cracked Hyacinth's skull open with a flying discus.
Loki from Norse Mythology is, among other things, Fenris's father and Sleipnir's mother, thanks to the power of shapeshifting, allowing him to seduce a jotun's horse., and a conversetion between Loki and Odin implies that Loki as turned into a woman and get pregnancy in more than one occasion. Loki is depraved in some ways, among them being responsible for Baldur's murder.
Huehuecoyotl from Aztec Mythology, has male and female lovers, is a Shapeshifter and often changes gender and species. While friendly towards humans, he's also petty and amoral at times and has been known to case war among mortals for no other reason than boredom.
Lilith had sex with both Adam and Eve, according to one passage in Jewish literature that describes her as "the Woman of Harlotry."
Both played straight and inverted by Dungeons & Dragons 3rd Edition. Malcanthet, the Demon Queen of Succubi, is the patron of lust and illicit sex, and she seduces both males and females. On the other hand, her enemy, Queen Morwel of the Eladrins, is the patron of sex between lovers and sensual energy turned toward positive ends, and she's bisexual and polyamorous.
Also played straight with another demon lord— Graz'zt, the Dark Prince, who keeps "pleasure slaves" of both genders.
King Kaius of Eberron is said to keep a harem of both women and men, he's really a vampire and feeds off of them.
Subverted in that he's actually a pretty nice guy. Well... Y'know. For a vampire, anyway.
Naturally, taken Up to Eleven by Warhammer 40,000 with Slaanesh, chaos god(dess) of hedonism. A violent, omnisexual rapist leading legions of daemons and cultists who are also violent rapists and tend not to care about gender much.
A fair portion of the Dark Eldar, an army of torturous slavedriving pirates, also tend to fall into Depraved Bisexual territory.
Exalted had the horrific Villain with Good Publicity First Age Solar Desus, a Fake Ultimate Hero who, as noted on the latter page, committed horrific acts of physical, mental, and sexual abuse on a routine basis against anyone unlucky enough to be in his path. He was also a Domestic Abuser who, among other things, would routinely force his Lunar wife Lilith to engage in Gender Bending to "spice up" their sex life, something she took no pleasure in even when he wasn't engaging in the sort of hardcore sadism only a First Age Solar can dream up.
Vamp and Volgin in the Metal Gear series. Volgin is something of a subversion, as his care for his male lover Raikov (he beats his female lover for fun) is the only humanising thing about him in the whole damn game, to the point where donning the Raikov mask causes him to be too stunned to attack you during your boss fight with him. Similarly, Vamp's whole motivation for being a terrorist is because he thinks Snake was responsible for the death of his male lover, and by extension ruining the life of his female not-quite-lover. He might be able to carve out your body parts and hand them to you, but his boyfriend was a good man.
Just as most of the bisexual part comes from her profile's Likes originally including "big breasts".
And she openly hits on people of both genders. She taunts Chun-Li via asking if she has "a schoolgirl's crush", refers to Cammy as "kitten", and when she's about to fight Bison she comments on how she was "saving the best course for last". One of her Ultrasoozes with Orgasmic Combat vibes (face stroking included!), and it can be performed on both males and females.
Depending on what you count as canon or not, Vega might count. He's been shown throwing roses to other bishounen male fighters in Capcom vs SNK and during a non canon anime series briefly commented on Ken's eyes.
Reaver from Fable II and Fable III. He's a sociopathic Magnificent Bastard Pirate lord who keeps his youth and good looks by sacrificing innocents to dark gods. He hits on the player (male or female) in a creepy fashion at least once in both games. And he's one of the protagonists.
Grand Theft Auto IV features several random encounters with Eddie Low. Easily one of the creepiest characters one will ever find in a video game, you can deduce just by talking with him that he is a necrophilliac and pedophillic serial killer who horribly mutilates and murders both girls and boys for sexual pleasure. So it's no surprise later on when he randomly tries to kill you as well.
Eddie: I like boys. I like girls too. Both are fun in different ways. The same ways as well. We're all the same under those layers of hair, and skin, and fat. Everyone's got the same rotten livers and black hearts underneath it all.
Clive Barker's Jericho features Cassus Vicus, one of the most Squick-inducing characters to have ever appeared in a game, is strongly implied to be bisexual. At one point, he comments on how it has been a while since he has "tasted of both sexes", although this comment could be a reference to his cannibalism, or it could possibly be used both in a cannibalistic and sexual context.
Lucas Arts have apparently claimed that bi/homosexuality doesn't exist in the Star Wars Universe. In a universe with so many alien life forms, those terms don't exist, and that all sorts of sexual inclinations exist with no one really caring about it enough to give it names.
Zevran has a Freudian Excuse; born into prostitution, sold into slavery and trained in kill or be killed; but still manages the Chivalrous Pervert. His constant innuendo seems designed to provoke for his own amusement.
Branka plays it seriously straight, exhibiting a number of sociopathic derangements.
Averted with Leliana. Killing wasn't the only method of her profession, nor one she preferred. While Zevran questions her about her life in the cloister, she admits she found some nuns more attractive because of their "forbidden" status, she was there for spiritual purposes, and not interested in ravishing anyone.
Lau in Family Project is viewed this way, and it's not entirely inaccurate. He set up the whole situation with Chunhua in order to set off a gang war that destroyed the Taiwan and Shangai mafia, leaving a power gap for him to move into. And also spread the rumor his sister was engaged to Tsukasa, a dangerous situation for him, in order to improve his reputation. Chinese mafia marrying a japanese into the family is a good business idea. He really did intend to go through with that one though. In reality, he's not so much a bad guy as he is very bad with people, and lonely.
Apparently, the Boss from Saints Row, at least the female version, though it's only really evident in 2. ("You had me at stripper pole.")
In 1 you can interpret a few actions and comments as an indication of the male Playa/Boss's bisexuality, but it is understandably left ambiguous.
Kefka's line in the original Japanese for Firon was more "You must be sweltering!" they were just added a ton of subtext in the translation with the way they went about it.
His comments on Firion can be seen more as a subversion, pointing out Firion's bishiness; his tone of voice is quite sardonic, not admiring or lecherous as you would expect. Calling himself handsome is obviously a joke.
Morinth in Mass Effect 2. She's a combination of a sexual predator and serial killer, seducing her victims with 400 years of experience and borderline psychic powers, and then kills them during sex (the asari version, anyway) by overloading their nervous systems due to her rare genetic defect, an act that brings her immense, addictive pleasure. Less of an example than most in that all Asari are effectively omnisexual.
Howard: Clearly you've never had sex with an onion!
Occasionally happens with a character in Rome: Total War. Observe this wonderful list of character traits:
Good Commander (He is an effective commander of armies. This we will soon see is not true.)
Publically Loyal (He claims loyalty to his country, but doesn't actually have any.)
Aggressively Perverse (He rapes other men)
Sot (Frequently gets drunk enough to soil himself)
Debauched (Will do anything for physical satisfaction)
Womanizer (What it sounds like)
Inveterate Gambler (Is addicted to gambling, and sucks at it)
One of 47's targets in Hitman: Blood Money is Skip Muldoon, a Corrupt Hick drug smuggler and riverboat captain. Muldoon is carrying on affairs with several of the male pursers on his ship, while simultaneously engaging in incest with his niece, photographic evidence of which 47 is also told to steal.
Preiss from Gabriel Knight: The Beast Within. Even Hennemann is scared to sleep in the same room as him. He also has a whip and a black rope in his closet.
The Courier can be one of these in Fallout: New Vegas by taking both the Lady Killer and Confirmed Bachelor perks. Or alternatively for female characters, Black Widow and Cherchez La Femme.
Relius Clover from BlazBlue is implied to be bisexual, and while he's not explicitly Ax-Crazy, he's still a cold, sociopathic monster.
Trevor Phillips from Grand Theft Auto V. Male, female, Mr. Raspberry Jam(A Teddy bear)...as his LifeInvaded page says "Any hole's a goal".
From Phantasmagoria 2, Therese is a dominatrix who regularly frequents an S&M club. Not so bad by itself, but otherwise she comes across as a complete nutcase. She stalks Curtis to make him her new lover and goes so far as to break into his apartment and install a bondage body harness in his bedroom without his prior consent while he was away. When he objects because he has a girlfriend (Jocilyn), Therese tells him that she's welcome too because she finds her a 'real cutie'.
Dead Rising 2 has twins Amber and Crystal Bailey, who are among the conspirators who triggered the Fortune City zombie outbreak. They constantly feel each other up, makes sexual taunts to Chuck Greene/Frank West, and grope Rebecca and force her to bend over when they kidnap her.
Dead Rising 3 has Dylan Fuentes, who kidnaps men and women and holds them in an S&M themed dungeon. When Nick Ramos shows up, Dylan expresses a desire to make him a sex slave as well.
Szark Sturz and Celesto Morgan from Dominic Deegan. Puzzlingly, using the phrase "filthy bisexuals" is a minor villain's Kick the Dog moment.
Boxed Crook Fitz, very much a pervert and habitual perpetrator of Grand Theft Me, responded to Tim and Zaha's mock-flirting with an enthusiastic "one Fitz fits all!" - T's writing style leads one to assume he's serious, at least about "fitting all" until stated otherwise.
Joel from Concession has slept with/seduced several of the other characters, either to further his plans or for his own amusement. He also once used his psychic powers to make a preteen child rape his co-worker Artie.
The scythe-wielding Fae in Keychain of Creation who introduced himself by kissing every member of the main party in turn.
Merena also edges on this trope. She's not actively malicious, but flatly doesn't care if her bed-bouncing ways wreck the homes and lives of the people she seduces.
Danny of Chess Piece, who has hit on his cousin Elliot on his wedding day. (Danny's, not Elliot's, that is.)
Zii of Ménage à 3 started out as a flirtatious Bi the WayLad-ette, but she was quickly flanderized into this, in supreme Jerkass form. She'll manipulate anyone she can into sex with either her or each other, all while working almost obsessively to keep others from getting any action that she doesn't approve of.
Fuschia and Baby Blue in Sinfestplay this role, although it's uncertain whether they're actually bisexual or just gay-for-pay (and both of them show positive emotions—Fuschia in a clearly romantic relationship with Criminy, and Baby Blue in a possibly romantic, possibly friendly connection to Fuschia that persists even beyond what's required for their job.)
Possibly Mistress Butterfly from Collar 6, also know as The Sadist From Hell. She has at least one confirmed relationship with a man, but she's tortured women on screen. She's also the closest thing the comic has to a Big Bad so far. This is not a case of Bondage Is Bad since the other characters in the comic are in consensual BDSM relationships, Butterfly is evil because she uses force, nor is it a case of same-sex attraction being portrayed as bad since the main characters are all in a poly lesbian relationship.
In Jack Drip, the incarnation of the sin of lust prefers to rape women, but he's not picky.
Damara Megido from Homestuck. All Trolls are bisexual, she just adds the 'depraved' part by having almost everything she says to another troll be crude sexual come-ons in badly-translated Japanese.
Tycho & Gabe from Penny Arcade. While showing little more then friendly animosity toward each other and both having wives, there has been many, many a gay joke where the boys have love shrines, nude photos, and plans to abducts and marry male game developers.
Female example: Melina Frost in Survival of the Fittest version three. She lead the all woman group named the Poison Angels in an attempt to kill all the men on the island. She was about as Ax-Crazy as it got. One of the best examples of her insanity is when she rapes Beth Vanallen. With a vase.
From SOTF-TV, Marvia Jones could also be an example. Her first appearance on the island? Getting high, drugging Nate Chauncey and taking advantage of her, culminating in beating her up and taking her things. She then proceeded to team up with Harold Smythe, who was probably among the most Ax-Crazy of the TV characters.
Anything I would do to a woman, I would do to a man as well. [...] I would penetrate a man just like I would penetrate a woman. That's why bisexual people are the only real equal opportunists out there.
For the third DVD promo, Doug himself played a shirtless, psychotic bisexual who was torturing a guy with a knife. Not necessary, but very much appreciated. The persona came back in a ConBravo interview, where he groped the interviewer and ended up riding him like a pony, he'd had years of experiences in sexing people up, he'd slept with both James and his wife, he was non-exclusively married to Benzaie, and he'd ruined JewWario's balls through getting teabagged.
Unusually for this trope, she's portrayed as being a genuinely nice and kind pony, underneath the questionable consent mechanics, undiscriminating tastes, and complete lack of impulse control. Given that she's gone after her own sister and tried to arrange a foursome with her student, her student's freshly married brother, and his wife, 'depraved' is probably still the right word.
MSF High Forum: Played with and Averted. Seram is, like a certain character from Dragon Age, both depraved and bisexual. However, there's not a real relation, and she retains her bisexuality after her Heel Face Turn. Michelle, meanwhile, completely averts it.
SF Debris: Parody Janeway has had either explicit or implied interest in a staggering number of characters. Male: her fiance Mark, her Harry Kim-shaped strap-on that may or may not actually be Harry Kim, Tom Paris (although they were both giant newts at the time), the inspector from Counterpoint, Chakotay, Captain Adama from Battlestar Galactica (Classic). Female: Torres, Seven of Nine, and herself. As for the depravity, anyone who offers drugs and cigarettes to small children they are training up to be loyal minions, breeds a "rape gorilla" and has created hives of flying tarantulas with a taste for ocular jelly probably has enough depravity to supply entire legions of demented Roman emperors.
Daniel Stopframe in Moral Orel is willing to seduce and impregnate the wife of Clay Puppington, the man he is obsessed with, just to get close to him, only to spurn her casually afterwords. He also prays to Satan in order to get who he wants and shows willingness to kill the guy's son as a virgin sacrifice as part of a Satanic ritual to get the guy to love him (luckily, his scheme gets shot down when he finds out that the Satanists of Moralton aren't down with that).
Stewie from Family Guy. Yeah, he's a toddler, but he's definitely depraved and has shown attraction to several people of both genders (such as Brian).
Possibly Meg. She spends her free time trying to get a boyfriend and in episodes like "Stew-Roids" and "Dial Meg For Murder" she appears to exhibit attraction towards Connie, a girl who constantly bullies her. Some episodes depict her being both emotionally fragile and disturbed, derived from a desperation for love and attention.
"Dial Meg For Murder" implied she'd been on both ends of multiple Prison Rape situations, in a women's correctional institution.
Eric Cartman from South Park. He was attracted to Ben Affleck (he gave him a hand-job in one episode whilst pretending his hand is Jennifer Lopez) and Michael Jefferson; dressed as Britney Spears in one episode and makes out with a Justin Timberlake cardboard cutout; had a sexual affair with Leonardo Di Caprio whilst convinced he's a Vietnamese prostitute due to a head injury; is obsessed with and follows Kyle Broflovski around (he even went on a cross-country quest just to make him suck his balls in Imaginationland: The Trilogy), blew Butters in his sleep after giving him cold medicine, then tried to convince Butters to do the same to him; and asked Clyde to sleep with him once (he was actually quoting "Lady Marmalade"; you know the lyric). But he also experienced attraction towards Wendy, Stan's girlfriend; mentioned that he had a crush on a girl named Patty Nelson; and had a crush on Bebe when she started developing breasts (along with the entire male 4th graders).
And Mr. Garrison, who seems to exist solely to defy "the norm". He was in the Transparent Closet at first, then came out as Camp Gay, then got a sex-change, then became a lesbian, then got turned back into a Camp Gay male. Chef summed it up in The Death Camp of Tolerance.
Chef: Children, there's a big difference between gay people and Mr. Garrison.
In the Daria movie Is It Fall Yet?, Jane goes to an art commune for the summer. The only girl who befriends her later gets her drunk and tries to seduce her, then sleeps with the pompous, famous artist who runs the commune, presumably in hopes of getting an in with gallery owners.
Sergeant Hatred in The Venture Bros.. Also a pedophile and strongly implied to have molested at least Hank.
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 is in a homosexual relationship with Stimpy, with whom he already shared an Ambiguously Gay relationship with in the original. He's also described as "psychotic", can be very sadistic, and frequently goes on Ax-Crazy rampages.
Pam Poovey and Cheryl Tunt on Archer. The former is openly bisexual and has been shown to be willing to go to unethical lengths for sex. The latter is batshit-crazy and really enjoys getting beaten, humiliated, and choked, and although she usually prefers men, she's been known to provoke women if she thinks they'll give her a good beating.
Roger Smith from American Dad! is a "fey pansexual" who is a total sociopath and (offscreen) rapist.