In Britain gay gangsters have always been a cultural staple, from Robin Hood and his Merry Men (in tights) to the two most famous British hoods of the last century, Reg and Ronnie Kray. When the police finally arrested them in a dawn raid, the press reported how they'd found Reg in bed with a girlfriend, and Ron in bed with a young blond lad.
What makes A Very British Gangster such a special film is that it takes you right inside one of Britain's most dangerous crime families. For the first time ever in Britain, a gang of contemporary criminals open up their lives to reveal their brutal world of guns and grinding poverty, the world of a hard bitten underclass that relies upon gangsters for justice, rather than police. And it's not make believe or dressing up.
Anime & Manga Nirasawa from Bi no Kyoujin is a Straight Gay Bishōnen evolving in the highly homophobic Yakuza world where he becomes the leman of Kabu, the heir of his clan. Kabu is particularly intrigued by Nirasawa's shrewdness and his resilience under torture which prompted him to take him under his wing as his Battle Butler.
In the Cowboy Bebop episode "Waltz for Venus", the crew burst in on a low-rank gang member in mid-coitus with his boyfriend in order to interrogate him about the whereabouts of his boss.
Asami is the local crime boss stalked by Intrepid Reporter Takaba in the Finder Series.
Gauron from Full Metal Panic! could count, though he's more towards the side of being a terrorist than a gangster. However, he does do shady dealings with smuggling in the underground world, and generally acts like one. His brutal, macho behavior is definitely a contrast to his twisted and obsessive love for Sousuke, making him a pretty good example of being a Straight Gay.
The leader of the G Boys in the manga of Ikebukuro West Gate Park is all but explicitly said to be gay. None of his underlings are though.
Ranmaru from Ikoku Irokoi Romantan is also a young Yakuza clan heir who marries his beard wife while falling for the cruise ship's captain who hosts their lavish wedding soirée.
Inuyasha: Remember Jakotsu of the Band of Seven? An extremely creepy Depraved Gayngster Yandere.
Minor villains Squalo and Tiziano from JoJo's Bizarre Adventure: Golden Wind, they are dedicated enough to each other than Tiziano doesn't hesitate to intercept a salvo from Aerosmith meant for Squalo. Also two members of La Squadra di Esecuzione, Sorbet and Gelato, were rumored to be a gay couple, which is more heavily hinted at in the anime adaptation. Everyone else, including the protagonists, comes off as almost Camp Gay due to their really weird clothes, but don't really show any attraction to the same sex. Or the opposite sex, for the most part. However, there are moments in the story where the protagonists express strong emotional feelings, akin to romance, for someone of the same sex. Abbacchio's feelings for Bruno is a good example of this. There are also times when two main male characters, Giorno and Mista, are placed in precarious situations simulating sexual acts.
Jin Lee and Yeong Joon in the Korean manhwa Kill Me Kiss Me are both part of the Yi Won gang, and romantically involved with each other. The only reason Ghoon-Hahm (the gang leader) doesn't "beat Jin Lee staight," is because Jin is the gang's money man.
Similarly Kizuna also focuses on the Yakuza setting, but in a rather less grim and more romanticized way.
Tsukuyomi in Negima! Magister Negi Magi is basically a terrorist (as far as Sayo is concerned). She's also an extreme Psycho Lesbian.
Kano from Okane ga Nai is also an example of this trope, of the Loan Shark variety. Likewise, his subordinate Homare Kuba is also an example, being a very dangerous brawler who also falls for his boss' lover Ayase, a dainty 18 years old boy.
The great Mr. 2 Bon Clay from One Piece is a rare Camp Gay version of this trope.
Paranoia Agent features a yakuza boss who's into younger men.
A lot of members from the mafia in Reborn! (2004) have extremely questionable sexuality... but for a more obvious, straightforward example, Lussuria from the Varia is shown outright to be gay.
In Shadow Star, a gang of thugs calls in a gay gangster for the sole purpose of raping the Wholesome Crossdresser who just gives an Unsettling Gender-Reveal before they kill the crossdresser.
Tsujido of Speed Grapher is implied to be gay and have a romantic quality in his devotion to his boss Suitengu. He and the other members of the Terrible Trio were implied to be involved in petty crime prior to being rescued by Suitengu in their backstory, and they are certainly gangsters during the series.
Nico of Tokyo Ghoul, a standard Camp Gay who is among the more prominent and influential members of ghoul gang, the Clowns.
Buppa, one of the mob bosses in Tokyo Tribes, is a Fat Bastard Depraved Bisexual who rapes boys so hard they explode. Really.
Yashiro from Twittering Birds Never Fly is a notoriously depraved example of the trope, being capable of beating up his foes singlehandedly while shamelessly using his position and attractiveness to seduce and screw with his superior or his fellow mob bosses, which elicits disgust and disbelief from his cohorts who greatly fear him but who also wonder how these dangerous mobsters could have sex with a man like him.
Jun Sekiya, the leader of the Toujou-gumi, in Wild Adapter is explicitly gay. Sanada, leader of the Izumokai, may be; he shows an interest in Kubota, but it isn't clear if he usually likes men or if its just Kubota.
Video Games Assassin's Creed Syndicate has Maxwell Roth, a brutal Victorian-era London Gangster and the mastermind of the Templar-controlled Blighters street gang. He has insane amounts of Foe Romance Subtext with the game's male protagonist Jacob Frye, and Word of Gay confirmed that his overtures towards him, such as giving him a "Take That!" Kiss before dying, were not intended to spite him but out of genuine attraction to him. Jacob himself counts as well as the co-leader of the Rooks street gang along with his twin sister Evie, since the same writer who confirmed Roth's homosexuality also said in the same interview that at the very least Jacob was written to be bi-curious, and his brief partnership with Roth was partly a form of self-discovery.
V in Cyberpunk 2077 can be played as this. While V can never become a fully-fledged gang member, they can take different jobs from fixers who have strong ties to them (like Wakako or Padre). While all Vs count for this trope, the ones with a streetkid lifepath are openly stated to be raised by different gangs. No matter their sexual orientation, V will always be a tough-as-nails mercenary. While the player can customize V's looks and make them look as camp as they want, V can't really act in a camp way (and, since kitch is the hottes trend in 2077, their looks might not mean much in-universe), so untill V hires a same-sex joytoy or starts dating Kerry Eurodyne or Judy Alvarez, nothing really points to them being gay/bi.
Sera in Dragon Age: Inquisition is an elven archer and rogue who works for the Friends of Red Jenny, a Karmic Thief gang that targets nobles for valuables and mischief to help out the common people of Thedas. She is also a romance option for female Inquisitors only.
Bambi "Buck" Hughes in Far Cry 3 is not a gangster, but he is a mercenary hired by Hoyt Volker, the leader of a massive slaver syndicate operating from the Rook Islands. As for being gay, he's keeping Jason's friend Keith as a Sex Slave to force Jason to find a Chinese knife for him, and he's pretty brutal with him. And when Jason finds Keith, Buck's eager to add Jason to his list of conquests. Apparently, he's not above "taking his meat rare" if he feels like it. Hoyt Volker himself briefly plays this for Faux Yay Black Comedy. After cutting off Jason's ring finger in a poker tournament, he says "Aw, Jason, now we'll never be married." Apart from this, we never learn anything about Hoyt's sexual preferences. He's more defined by selling slaves and killing people than raping men.
Final Fight has Roxy and Poison. Roxy is, as a fancier of Poison, somewhere in the LGBT spectrum. And she's in a street-fighting gang. As for Poison... well, you can pick and choose (literally - latest Word of God is "pick for yourself") between whether she's a woman, a cis woman, a transsexual woman, or an intersex woman, so she could fit in this as well.
Many games in the Fire Emblem franchise feature two bandits, one pink, one blue that are quite clearly masochistic, and in some cases incestuous, homosexuals.
Grand Theft Auto: El Burro in the original Grand Theft Auto. After you complete level 4 (second level of San Andreas), you are summoned to his club where he tells you he is "gonna reward you personally this time!" Funnily enough you then zoom over to Vice City for the next level.
Implied in the case of Kazuki Kasen in Grand Theft Auto: Liberty City Stories, whose wife Toshiko states that he "prefers the company of men" and hires Toni to kill him because she wants out of a loveless marriage.
Gay Tony in Grand Theft Auto IV: The Ballad of Gay Tony is not a gangster himself, but runs a nightclub that has regular dealings with gangsters. And his protégé Luis, while also not a gangster, does a lot of freelance work for gangsters.
In the "Death on the Mississippi" mission of Hitman: Blood Money, among the player's targets is Skip Muldoon, who runs a cruise ship business on the Mississippi river, and who is also a Depraved Bisexual gang lord who is very bluntly implied to force his male ship staff to sleep with him.
In Mafia III, Nicki Burke, a high-ranking member of The Irish Mob, is gay.
Mass Effect: Aria T'Loak, the "Pirate Queen" of Omega in Mass Effect 2, is omnisexual like all asari, but it's obvious she prefers the company of women upon playing through the Omega DLC of Mass Effect 3.
Captain Gavorn, a minor Non-Player Character who serves as an enforcer in Aria's organization, is heavily implied to be gay in video footage you can view in the Lair of the Shadow Broker DLC for Mass Effect 2.
Reyes Vidal in Mass Effect: Andromeda is a human Exile who has established a name for himself as a smuggler and criminal on Kadara, and is bisexual and available as a romance option for a male or female Ryder. Bonus points for being revealed as the Charlatan, the criminal mastermind behind the Collective.
Kanji in Persona 4; he isn't in a gang, or part of an organized group of any kind beyond the Investigation Team, and he's only Ambiguously Gay with a side of Sweet on Polly Oliver, but he acts and dresses like a Japanese Delinquent in order to cover up the shame of his enthusiastic love of traditionally-feminine things.
Streets of Rage 3 for the Sega Genesis had a stereotypically gay miniboss named Ash. Of course, he got Bowdlerized when the game was ported to the United States.