Patrick Bateman of American Psycho (in the film adaption as well where he's portrayed by Christian Bale) In one scene Bateman is about to kill his associate, Luis, by strangling him from behind, but Luis mistakes this as Bateman coming onto him, causing him to reveal that he's gay and in love with Bateman.
Ascendance of a Bookworm: Ferdinand, the cast Sexy Priest, has plenty of female admirers. When his disciple with Past-Life Memories of modern-day Japan introduces picture printing to the setting by mass-producing flattering illustrations of Ferdinand, they sell like hotcakes. Later, two of Ferdinand's male retainers, one of whom is a widower, turn out to have been among the people who purchased the illustrations.
Late in Between Worlds there's a sex scene between Jason and his male squadmate Tarcil. Jason isn't attracted to human males, but for reasons even he isn't sure of, it doesn't seem the same to experiment with a Shil'vati male (though they don't repeat the experiment).
Daemon, from the Black Jewels series, manages to use this, along with everything else sexual, as a weapon. Paraphrased:
Rainier: (who is a homosexual male, and is dancing with Daemon) You can be a sadistic bastard when you want, can't you? Daemon: Ah, but you'd let me hurt you, wouldn't you? [temperature drops a few degrees] Rainier:[says nothing, but looks very, very scared]
James Emerson Fletcher of the Bloody Jack series. Clementine's father and a few others want him.
Child Ballads: In Ballad #100, "Willie O' Winsbury", a king threatens to hang the man who got his daughter pregnant, but when he meets the eponymous Willie O' Winsbury he's stunned by Willie's good looks.
"And it is no wonder," said the king, "That my daughter's love you did win. If I were a woman, as I am a man, My bedfellow you would have been."
A very dark example occurs with Acheron in the Dark Hunter series — since everyone wants him, the guys do too. This often ended badly for him, especially as a child.
Thomas of The Dresden Files is a supernaturally-sexy White Court Vampire, and this is a good thing in his usual circles but causes problems when he must walk among Muggles. When he brought up how hard holding down a job was given what happened to women when they got around him, Dresden says something to the effect of "At least it was a woman that time." An apparently straight male character once said of him (when believing him to be Dresden's lover) "it's okay, even I notice how good he looks."
Ender's Game: Alai has what is very strongly implied to be a crush on Ender.
Adam from Eve and Adam. Everybody wants him, regardless of gender or sexuality.
Eric of Every Fifteen Minutes by Lisa Scottoline has three woman that have expressed interest in him. Also, his attorney Paul is very friendly with Eric, jokes about their interactions being "foreplay" and says Eric looks "damn good" when he dresses up. Paul also informs Eric when he does something badass: "I might be in love with you".
The Fault in Our Stars: Augustus, as Isaac points out Augustus’s “physical attractiveness” multiple times.
The titular Harry Potter gets attention from a lot of obsessive fangirls, Cho, Ginny, and one fanboy (Collin Creevey). Not to mention that many fans noticed Harry's tendency to describe good looking men (probably due to JK's female gaze is writing Harry's POV).
Christopher Marlowe's poem "Hero And Leander" practically name-drops this trope. It barely describes Hero, the beautiful woman, but Leander is described in detail, as a really hot guy. Then, this happens:
Had wild Hippolytus Leander seen Enamoured of his beauty had he been. His presence made the rudest peasant melt That in the vast uplandish country dwelt. The barbarous Thracian soldier, moved with nought, Was moved with him and for his favour sought. Some swore he was a maid in man's attire, For in his looks were all that men desire.
Translated into Modern English, that says: "So hot even the guys want him, even guys who like hunting better than sex. But we're straight guys, so he must be a woman in drag!"
Hoot: In the film, Roy's odd obsession with Mullet Fingers.
Implied with Finnick in The Hunger Games, whose admirers (or rather, patrons) are always mentioned by gender-neutral terms, and their genders are never mentioned in the text.
In the Hurog duology, there are some examples. Ward treats it as a fact that a pretty slave boy will be in danger of being molested by men, and when he meets Garranon, the king's "favourite", he can easily imagine why the king wants him. Garranon is Happily Married to a woman, and actually more of a Sex Slave to the king than anything else.
InCryptid: Incubi like Ted Harrington and his son Artie produce pheromones that make anyone who's attracted to men be attracted to them. It's even worse if they bleed; Antimony found out her dad was bi when he made a pass at a bleeding Ted, and Artie took advantage of his blood to snap James out of a mind-control haze (though he was able to control himself enough to get away and take an antidote).
De Quincy and Magnus Bane both hint at this about Will.
Of course this applies to Magnus Bane as well since De Quincy was interested in him, "as more than friends". Tessa didn't know what Magnus was hinting at, but that was because such things were unheard of in such a time period... (or just not talked about).
Luke Sunborn from In Other Lands. He is the most popular boy in the camp and is highly admired by everyone because he comes from a famous warrior clan. Elliot, the protagonist, attempts to set him up with his crush Dale Wavechaser, who is the only other gay guy at the camp besides Elliot. Elliot doesn't like Dale much so he tries to set him up with his straight friend Peter instead. Even though he doesn't like guys, Peter actually considers it when told the Luke Sunborn might like him and is visibly upset when Luke makes it clear to Elliot that he's not interested in Peter whatsoever. Elliot invokes the trope when he complains that, compared to him, Luke had such an easy love life that not only did his crush clearly like him back but also even guys who didn't like guys were open to dating him.
In The Kharkanas Trilogy Finarra Stone asserts that young Spinnock gets plenty attention from all genders.
Spinnock Durav had been pursued by women and men since he had first come of age.
Knight Life Series: In the original Knight Life, a TV reporter comments that he's almost tempted to turn gay for Arthur Penn (secretly Arthur Pendragon, one time King of the Britons.)
Kushiel's Legacy: Alcuin and Delaunay are both bisexual with more notable male lovers than female ones. Averted with Joscelin when he and Phèdre are sold into slavery. The Skaldi women find him, um, desirable, but the Skaldi men thinks he's a pretty-boy with no beard. At least, they acknowledge his "manliness" when he kills one of their own in a sanctioned duel.
Raziel of Lamb: The Gospel According to Biff. Ave. the decidedly straight male protagonist who hates the angel's guts admits that he's probably the prettiest thing he's ever seen.
Francis Crawford of Lymond in Dorothy Dunnett's Lymond Chronicles. His male lackeys always seem to fall in love with him, even his sister wants him, and in one book he screws half the French court. In the first book, even the prosecutor at Lymond's trial says if he were ten years younger and a girl, he'd woo Lymond.
In Mind Games, the first time Anthony sees James after his Charisma stat boost, he says, "I'm straight as a ruler and you're looking kinda tasty."
Aiden from Of Fear and Faith mentions that his charms work on men as well as women and he occasionally takes advantage of this, flirting with them to get what he wants.
In the Outlander series, it's rather ironic to note that Claire's husband Jamie seems to end up having more male admirers than Claire herself. The author must be a Yaoi Fangirl. Especially interesting in the case of how her husband from the present's ancestor Captain John Randall (who looks identical to him), was almost made to look like a romantic interest for Claire in the past timeline, only for him to become obsessed with Claire's husband and hate Claire because he's jealous of how she's Jamie's wife. Also, the Duke of Sandringham apparently tried (unsuccessfully) to do Jamie when Jamie was young, as well.
Oscar Wilde wrote a couple of these. Author Appeal—he was a gay man himself, but lived in a time when openly writing about gay men was not marketable.
Apparently, Hughie Erskine from the Model Millionaire. In the first page he is described as really handsome and "as popular with men as he was with women".
Song at Dawn Dragonetz tries to avoid romantic interest in himself yet even men Such as crossdressing lady Sanchez are in love with him.
The novelization of the original Star Trek, specifically the episode "Who Weeps for Adonis?", has Bones telling Kirk about the medical mystery buried in Apollo's "gorgeous chest"; then again, Greek god.
El Draco from Oksana Pankeeva's Strange Kingdom Chroniclesuntil he was mutilated and raped by really BAD guy who wanted him. He was not only raped, but tortured so badly that it took corrective surgery to make him looking normally, let alone handsome. Anyway, his charisma still remained and the scars only attracted the girls.
Hikaru Genji from The Tale of Genji was known to inspire men to weep from his beauty. Of course, Everyone Was Bi back in the Heian era, so it wasn't as much of a big deal. Not just Genji; a lot of the beautiful men in that story spend a lot of time surreptitiously admiring each other and thinking "Man, if he were a woman, I'd totally do him... You know what, maybe I'd do him anyway."
Imai Kanchira from the Tomoe Gozen Saga is repeatedly stated to be as pretty as a girl, to the point that his sister's husband flirts with him because of their similar appearance.
In The Vampire Chronicles, Armand, so, so much. And Lestat. And Louis. And Nicolas. And Marius. A good deal of the series is built on this trope.
Alexis Papadopolis of Venus in Furs. When Severin first encounters Alexis, he's equally distressed by Wanda's instant infatuation and empathetic to her attraction to the man:
I now understand the masculine Eros, and I marvel at Socrates for having remained virtuous in view of an Alcibiades like this.
Irial from Wicked Lovely. Niall, too. Remember the scene with Seth lusting on him in Fragile Eternity?
In The Zombie Knight, Imas, a confirmed lesbian, has a crush on Jackson.
(fourth paragraph) of the Doctor Who Expanded Universe's Fitz Kreiner, despite the fact it's never really brought up in. the text. He's a bit of a Ho Yay magnet, but he's never treated as any sort of Stupid Sexy Flanders and no one ever seems to remark upon his quietly intense charms.