Brokeback Mountain: While the main characters, Ennis Del Mar and Jack Twist, are unambiguously in a secret relationship, many a debate centers on their exact sexuality – whether they're gay, bisexual, or not attracted to any men but each other. Though most people seem to at least think Jack was definitely gay, Ennis' sexuality is much more difficult to pin down.
Dates back at least as far as the silent film Way Down East, in which Lillian Gish's aunt is obviously coded as a lesbian (top hat, mannish glasses, brusque manner).
The Riddler in Batman Forever displays a lot of stereotypical hyper feminine camp gay mannerisms and is practically a Stalker with a Crush towards Bruce Wayne, AKA: Batman.
In Cavalcade, the Best Picture winner for 1933, there is a quick shot of a nightclub in which a woman wearing a monocle holds another woman's hand, and a man puts a bracelet on another man's wrist.
Theodora in the original The Haunting (1963). Extremely blatant when seen with modern eyes, and pretty much spelled out for us in this scene.
[Theo and Nell had been arguing over Nell's growing crush on Dr. Markway] Theo You poor stupid innocent. Nell: I rather be innocent than like you! Theo: Meaning what? Nell: [scoffs] Now who's being stupid and innocent? You know perfectly well what I mean. Theo: Is this another one of your crazy hallucinations? Nell: I'm not crazy! Theo: Crazy like a loon! You expect me to believe you're sane and the rest of the world is mad? Nell: Why not? The world is full of inconsistencies. Unnatural things, "Nature's mistakes", they're called... you, for instance! [Theo recoils in shock, is about to say something when they are interrupted.]
In the 1931 gangster classic The Public Enemy, there is a scene right after Tom Powers (James Cagney) comes into a lot of money where he is getting measured for a new suit. The tailor has a bit too much fun taking the measurements... Can be viewed here.
Ryan Evans from High School Musical. While Word of God will never admit it, the second movie throws in little hints such as his father trying to "straighten" out his increasingly flamboyant hats. Not to mention Ryan and Chad's homoerotic dance number "I Don't Dance" in the second movie, which was followed by a scene where they sit real close and, oh yeah, are wearing each other's clothes. And eating hot dogs. As of the stage version, he's officially out.
According to Molly Ringwald, one of the reasons Pretty in Pink's female lead wound up with a different guy than the producers intended was because members of the cast couldn't buy her platonic friend, Ducky, as heterosexual. (Even though he was, as his very last scene makes clear.)
Ozymandias in the film version of Watchmen. He hangs out with the Village People and David Bowie in a montage and has a folder called "Boys" in his computer. Not to mention his suit having Pharaoh Nipples.
In the 2007 3:10 to Yuma movie, no one ever comes straight out and says Charlie Prince is gay. But he struts like he's doing the catwalk, talks with a shrill high-pitched voice, has the best fashion sense of all the cowboys in the movie, and even wears eyeliner. The beautiful and well-endowed bar hostess that Ben Wade is attracted to earns a look of contempt from him, and throughout the whole movie, a big unspoken explanation for his incredible obsession and loyalty to Ben Wade is that he's in love (but they are still True Companions, when Charlie actually talks about why the gang should help him). The closest dialogue that hints at his sexuality is a Pinkerton calling him "Charlie Princess."
Wade Wilson, a. k. a. Deadpool in X-Men Origins: Wolverine. While no one actually says it, it's heavily implied: first, Victor (Sabertooth) says, "I thought you didn't like girls, Wade." Immediately after that, Wade jokingly offers Victor a manicure with his katana. A couple of minutes later, when everyone is stuck in an elevator, Wade says, "I'm stuck in an elevator with five guys on high-protein diets. Dreams really do come true." It doesn't help that he's played by Ryan Reynolds. However, all of these examples could be interpreted differently: claiming someone is homosexual is just an immature means of emasculating them, offering to give Victor a manicure with his katana could have just been a crack about his long claws, and the "high protein diets" comment could be a fart joke.
It's probably intentionally this, as the Deadpool of the comics is pansexual. Reynolds has been fairly vocal about wanting to incorporate that aspect into the solo movie(s), as well.
At least to a modern viewer, Addison DeWitt from All About Eve comes off as rather camp.
Eve herself is sometimes seen as being a lesbian or bisexual considering her androgynous appearance, her rough voice, and a scene with her walking with another unnamed woman, arm-in-arm, up the stairs in bathrobes. Given Eve's habits of deception, it's hard to pin down just what she is.
Ariel, Harris's best friend in L.A. Story is implied to be a lesbian. She lives with another woman, displays no romantic interest in men and the few discreet references to her sex life are gender neutral ("I hate to tell you this, Harris, but if you can find somebody you can have sex with and lie in bed and watch TV, you've really got something.")
In The Wrestler, Randy's estranged daughter Stephanie lives with another woman with whom she at the very least shares a very close friendship. Randy himself suspects that's she's gay, but it's never really confirmed one way or another.
In Amazing Grace it seems that William Wilberforce and William Pitt the Younger have a thing going on with each other. As in Real Life, they were apparently both buried near each other in Westminster Abbey. It also doesn't help that Pitt the Younger was widely rumored to be gay.
A Nightmare on Elm Street Part 2: Freddy's Revenge: Everything Jesse does or says basically comes out as gay, even though the entire time he wants to woo the lead female. He goes to a gay bar, runs away from a straight sex scene, dances and lip syncs to a girl pop song while wearing sparkly star sunglasses, even the actor who plays him is gay! The dialogue taken out of context comes off as so gay it hurts. And in all honesty, it wasn't a bad film. Remember it for your next homosexual get-together on Halloween!
Jesse: Something is trying to get inside of me. Ron: Yeah, it's female and it's waiting for you in the cabana, and you want to sleep with me.
Donald in Scotland, PA. The implications get pretty thick by the end, but he remains closeted; he does live in a small town in the 70's.
Rob Paulsen's character Larry the male stewardess in Stewardess School is extremely flamboyant and once during an emergency he asks for a bobby pin only to put it in his hair.
Hercules Returns, a Gag Dub of an old Italian Sword and Sandal flick, turns the eponymous Hercules into this. It's even turned into a minor plot point - a character pretending to be Zeus tells Hercules his purpose in the city of Chlamydia is to openly reveal to the world his true homosexual tendencies. Hercules, for his part, vehemently denies being gay.
Hercules, in a huff: Never heard anything so ridiculous in all of my life. Me, of all peop - My God, what if he's right?! Oh, of course he isn't.
In the 2009 The Taking Of Pelham 123, John Travolta's character Ryder exhibits some gay behavior. He says that Denzel Washington's character has a "sexy voice" and says he would have made Washington his "bitch in prison." When he finally meets Washington, Ryder says he's handsome and later asks how much he weighs for no particular reason. Ryder also comments on the fashion of a young man and says "he makes it work." However, Ryder also brags about taking a female "ass model" to Iceland after a party. It's hard to tell if he's really attracted to men or just being flippant.
Missy in Bring It On is described by other characters as "dykeadelic", follows Torrance around like a puppy dog, and the only time she shows interest in a man is when she finds out that he's gay. "You speak fag?"
Vasquez in Aliens is suggested to be a lesbian by the other marines, but it's probably just because she's a butch ladette. She seems to be close with Drake, though there's no overt sexual flirtation and they've got the same job.
Champ from Anchorman: The Legend of Ron Burgundy. The companion film, Wake Up, Ron Burgundy, which is made from footage left on the cutting room floor, makes Champ's attraction to Ron painfully explicit.
Leland the "Broadway critic" in Citizen Kane (ambiguous by nature of the Hays Code)
Played for comedy in OSS 117: Cairo, Nest of Spies. Agent 117 has dreamy recollections of time spent with his old buddy frolicking on the beach, which are humorously homoerotic. Later, he states with un-due force that two men having sex is totally disgusting, suggesting that he's closeted and "protesting too much."
In Go, two male Hollywood actors are forced to have a dinner date with the cop who arrested them to get on his good side. Whenever they cop and his wife are in different rooms, they both seem to be hitting on the actors, but the actors can't quite be sure. It turns out that the cop and his wife were just buttering them up to to sell them an ersatz Amway.
Just about any character (at least if it's a comedic one) portrayed by longtime Disney actor Ed Wynn comes off as this sooner or later (Uncle Albert in Mary Poppins, for one) due to his high-pitched voice and giggling. Interestingly, son Keenan Wynn (also a Disney actor at times) was known for having a much more masculine screen persona. Lampshaded by Matthew Perry when he appeared on Saturday Night Live.
Assjuice from Neighbors, says he was awake when Teddy put his penis in his mouth.
Ugarte from Casablanca seems a little too desperate for Rick's approval.
Pierre from Pocketful of Miracles (the remake of Lady for a Day). Pierre is one of the crew of makeup artists, etc. that Queenie Martin brings in to give Apple Annie a complete makeover. They all head into the bedroom and the dialogue goes something like this:
Dave the Dude: Hey, he [Pierre] can't go in there!
Mannequin: Arguably Mr. Richards, who, while not as flamboyant as Hollywood, has his gay moments.
The Uninvited: Miss Holloway, the woman who once was a nurse in the Meredith household, is coded as a lesbian who was in love with Mary Meredith. She seems way too fond of Mary, having named her sanitarium after Mary and hung a huge portrait of Mary in her office. She refers to Mary as "darling". She reminisces to Rick and Pamela about how she and Mary would sit up together and talk about how they were going to conquer the world. (And the hint of a lesbian relationship would explain why Mary was apparently willing to tolerate her husband's affair.)
Jillian Holtzmann in Ghostbusters (2016) is assumed to be lesbian by many fans and critics, because of her mildly Butch Lesbian dress sense and flirtatious attitude to her female team-mates, and because her actor Kate McKinnon is lesbian in real life. The film's director and co-writer Paul Feig has confirmed that she's gay in interviews, but the on-screen portrayal is subtext-only.