Leonard:[regarding girls flirting with him] Trust me, it doesn't [happen]. Alex: I don't know, you're cute, you're funny. Maybe you are getting hit on and don't even know it. Leonard: Really? Alex: ...pretty sure. [gives him the Puppy-Dog Eyes] Leonard:[ponders it for a moment]Hahahaha, I got to get back to work, thanks for listening... hope no one rips my clothes off on the way!
A character who is his own worst enemy when it comes to love. In fact, he's pretty much his only enemy in this arena. Wherever they go, it seems that for some reason they attract some romantic attention, in theory there is no reason why they couldn't go on to be The Casanova with a new person every night. The only problem is they are so unfamiliar with the dating scene they don't realize the girl who is hovering around him, batting her eyes, trying every excuse to make physical contact with them and suggesting they go back to her place qualifies as flirting and not simply being friendly.
Usually deliberately designed to be Mr. Fanservice. This character also tends to be Adorkable. Compare Accidental Pornomancer, Celibate Hero (who avoids romantic involvement that might interfere with The Cause) and Chaste Hero (who's too young, dumb or asexual to even be interested). See also Single-Target Sexuality, in which a character remains uninterested in potential love interests because they're only interested in one, Oblivious to Love, where there is one specific person who is clearly head-over-heels for them but they don't realize it, Chick Magnet (of course), Unwanted Harem and Hollywood Dateless. Remember that this character does not have to be male, although it usually is.
The titular teacher has this bad, as at least 15 girls, and there's only two that he's aware of. That's because two told him to his face that they love him. Naturally, this usually causes all sorts of problems, as he's extremely prone to I Didnt Mean to Turn You On type actions. To say nothing of the time when he accidentally leads on one of his students while she thinks that he's his own cousin.Chisame even points out that he's going to make a lot of girls cry in the future. Oh, and did we mention that he's still just 10-years-old? The scene that show this the best is when Akira tell him about some girls that like him, and he is completely shocked.
Akira: At this rate, I guess he doesn't know about Class Rep...
Kotaro has a case of this; even while still in his Girls Have Cooties phase he still has 4 girls, although he is starting to be aware that one of them might like him. She eventually has to literally beat it into his head before he gets the idea.
Hayate is an interesting case: He's not a Chaste Hero, in theory — he understands the idea of romance and attraction, and has a couple girls he's pining after, but he doesn't notice that every girl he meets falls in love with him. Yes, including the two he's in love with. The guys at school call him the Airhead Gigolo because of this: Part is his personality, part is just dumb luck, and there's even a little bit of Friend to All Living Things thrown in just for the hell of it.
It's shown that he is somewhat aware of his affect on girls and can actually play it up when he wants something, similar to his 'business smile' that he uses periodically. This often includes conjuring up love bubbles and bishie sparkle for extra charm. Possibly an extension of this is Hayate's 'Serious Mode' which ramps up his charm and charisma ten-fold and is even said to change the air around him with his confidence. To date it has been used exactly once; to make sure his date with Hinagiku was a complete success.
Hayate is deliberately inflicting this on himself however, stemming from what happened with Athena as a child, he doesn't seem to believe he deserves to be loved, and thus even if he is aware of the girls feelings about him, he won't act on it for that reason.
13-year-old Wataru's doing pretty well himself. He has, mostly unwittingly, gathered the attention of several girls (Saki, Sonia, Aika, and possibly Sakuya), all of whom are older than he is. Well, an exception is that Wataru has been made all too aware about Sonia's affection for him.
Yoshii has three girls pining after him: Minami, Himeji, and Minami's little sister Hazuki. At one point, Minami uses the threat of death to blackmail a date out of Yoshii, and Himeji makes lunches for him every day (which is a very bad thing, but its the thought that counts). Yoshii never notices. Ever. He does know that Hazuki loves him, but that's because she loudly insists they're getting married when she grows up.
Another notable one was when Yoshii's sister noted in front of Yoshii, Minami, and Himeji that Yoshii seems to only read porn about busty women in ponytails. Himeji immediately ties her hair into a ponytail, and the next day Minami (who always has a ponytail) comes to school with some sort of inflatable inserts. He still doesn't notice.
There are subtle hints in the novel that Hideyoshi might have a small crush on Yoshii too... and Kubo.
Kämpfer's Senou Natsuru: The densest material ever. The best example has to be Senou's date with Shizuku. He assumes its Not a Date... but she corrects him that no, it really is a date. He assumes she's joking. Cuz she does that all the time. Which then causes Mikoto to give him a couple of Megaton Punch attacks. Even Akane goes to his house afterward to find out why he took Shizuku out on a date, forcing him to take her on one as well in the next episode.
Shinji Ikari from Neon Genesis Evangelion. Somewhat subverted in that all of his potential romantic interests have major issues as well, which would make starting anything with them difficult in the best of cases. That being said, Shinji could stand to be a LOT more assertive himself.
Kamijou Touma. Between his heroic tendencies and misfortune, every girl he meets falls for him in short order. But because of the aforementioned misfortune, he just assumes they're all screwing with him. Or doesn't notice at all, though that one is at least a little justified by the fact that he lost his memory and didn't have the heart to tell anyone.
It also appears that alcohol functions as some sort of Amplifier Artifact on his ability to do this as well. When he gets drunk in Volume 2 of New Testament and starts wandering around Academy City, women just.... appear out of nowhere. In the end he takes no less than ten women home, simply through the virtue of walking to his apartment.
Misaka Mikoto:[seeing this process underway] In no time at all, they were in all directions.
Kotetsu from Tiger & Bunny is more of tsundere magnet than an actual Chick Magnet, but he is nonetheless oblivious to this ability. He just wonders why certain girls [namely his wife-to-be (during their high-school days) and Karina (during the course of the show)] keep acting all weird and contradictory around him.
The Title Character of Naruto can come off as this, especially in fillers with the countless Girl of the Week that start to like him.
Shuto Katsuragi, the titular Anti-Hero/Anti-Villain known as Ratman, is completely oblivious to the idea that his classmate Mirea Mizushima (who is part of the "evil" organization who turned him into Ratman) and RioKizaki (daughter of the Hero Association's president) are interested in anything more than being nice and friendly to him. This even extends to a Ho Yay version where Shiki constantly calls him cute and has No Sense of Personal Space, he just sees him as a friend and doesn't even seem to notice Shiki is disturbingly rather close to him.
High School D×D: Ironically enough, Hyodou Issei (a Harem Seeker!!) is one. This is justified because he has a huge inferiority complex after his first girlfriend killed him on their first date. However, the trope is later defied when his denseness finally gets to Rias enough to make her cry, at which point the rest of the harem hits him over the head with the fact that they really are in love with him. He then confesses to Rias, and they begin going out.
Ryuuichi from Gakuen Babysitters is one of the most fawned over guys in the class aside from Kamitani. However, he doesn't notice this, even when there are two girls showing much more obvious signs of attraction. Kamitani's case, however, is ambiguous, since it's difficult to tell from his personality whether he's actually clueless or just doesn't care.
Infinite Stratos gives us Ichika Orimura. He seems like one of the most impossibly dense harem protagonists, tied for first place with Senou and possibly Negi. He misunderstands Cecilia's sudden friendliness, Rin's promise to "cook for him every day", and Houki demanding he date her if she wins a tournament. However, the light novels (which are from his perspective) make it clear that he's not quite as bad as he seems, and is faking at least some of it, possibly so that he doesn't have to choose between five angry girls with Powered Armor.
Tomoe from Kamisama Kiss. He is completely oblivious to the fact that most teenage girls find him attractive and he fails to notice the signs that Nanami is starting to fall in love with him. Which is odd considering how much he likes hanging around in the Red Light District.
Godou Kusanagi in Campione! is this trope personified. Despite the fact that he's at least kissed four girls, he still thinks of them as friends. In this case, it's partially ignorance, and part Selective Obliviousness.
Eita, unwilling protagonist of Ore no Kanojo to Osananajimi ga Shuraba Sugiru. Every female character with significant screen time is madly in love with him, and there's some Ho Yay vibes from his best friend; but he's so determined to be a Celibate Hero that even while four cute girls are hanging around him and openly fighting for his attention, he doesn't really seem to understand what's going on. Or he wants to pretend it isn't happening.
Parn from Record of Lodoss War. Both Deedlit and Shiris are interested in him, but he doesn't seem to realize it and he remains a Celibate Hero throughout the series.
Monkey D. Luffy from One Piece. Even though Post-Gonk Alvida, the whole of Amazon Lily, and 'The World's Most Beautiful Woman' Boa Hancock are all in love with him, he still remains a clueless and Celibate Hero.
Where does one begin with Spider-Man? From boyhood he seemed to have the amazing ability to make extremely pretty girls fall in love with him only to be completely oblivious to it half time and have his secret ID ruin it for him anyways once he finally manages to figure it out.
Nightwing has almost a dozen women who are totally attracted to him without even trying.
The BlackKnight is described on a number of occasions as being a "hunk", manages to attract at least five different specific women that we hear about — three of them at the same time — and also at one point draws the appreciative eyes of a cruise ship full of staring women. Yet he often acts like he's got no chance with the ladies and acts pleasantly surprised and eager to please whenever a woman shows him any attention.
[[My Little Pony: Friendship Is Magic (IDW) issues 9 and 10 treat Big Macintosh this way; over of the course of the issues, at least three different mares (Fleetfoot, Tealove, and Princess Luna) show varying degrees of affection for him, and he never catches on. And that's not counting the numerous characters who make eyes at him, or Photo Finish, who attempts to shanghai him into a modeling job.
Pirates of the Caribbean: Will wastes all his frustrated energy on swordplay because he's about the only person who can't see that Elizabeth is ready to jump his bones the minute she can get him alone. Jack Sparrow even lampshades this at one point. Granted, he may be aware of it; he just thinks that due to their difference in social class (he's a blacksmith's apprentice and she's the governor's daughter), it would be downright disrespectful of him to have feelings for her. This can be seen in his refusal to call her anything but "Miss Swann" for most of the movie, even though she keeps telling him to call her Elizabeth.
A Princess Of Mars:
John Carter of Mars just could not get it through his Heroic Skull that the most beautiful woman of two worlds was head over heels for him. She had to beat him over the head with an "I love you" stick.
John Carter frankly admits he doesn't understand women but he does become clued in enough to recognize when other women fall in love with him — as they do with monotonous regularity to his considerable embarrassment. He develops an interesting strategy for dealing with the problem; he takes the girls home to Dejah Thoris. She apparently befriends them and sees to it they meet lots of attractive and available men until they find one that makes them forget John Carter.
Dag: Among Lakewalkers, a woman invites a man back to her tent... Fawn: Among farmers, the boy asks the girl... Dag: Really... How much time do you think we've wasted here, Spark?
Oddly gender-flipped in L. M. Montgomery's Anne of Green Gables series. Anne has such a warped, idealistic view of what love and romance is that she doesn't realize that there are half a dozen men waiting in line to marry her. Including her former enemy turned friend, Gilbert Blythe.
Derek of the web-novel Domina is continually blind to everyone's affections for him. Once, when two girls are having a heated argument over who gets his First Kiss, he thinks they're screwing with him.
Miles Vorkosigan is a lot more attractive to women (and one hermaphroditenote Who is explicitly said to be falling for him shortly after they first meet.), for all his bodily deformities, than he even begins to realize — though his cousin Ivan surely does. He later begins griping that while he can find women to love, none of them will marry him. And most of the women who fell for him did so without any real effort on his part. Both times he does try, it doesn't go well. Elena married another man, and Ekaterin nearly kicked him out of her life entirely, since he did it dishonestly.
Firestar from Warrior Cats didn't know Sandstorm and Cinderpelt were in love with him until the latter tells him about the former. As Erin Hunter jokingly said: "Stupid man cat!"
Darryl, the protagonist of Heart In Hand. When an attractive woman at a nightclub mentions that she's cold, talks about "wanting something to warm me up" and spills a drink over her top, his only reaction is to give his sweatshirt to hernote yes, he wore a sweatshirt to a nightclub.
Live Action TV
Clark Kent in Smallville. He has more girls after him than you could count, but Chloe's long-time crush on him probably fits best, thanks to him being completely Oblivious to Love until Pete points out she's in love with him. Harsher in Hindsight when in Truth it is revealed Pete had a crush on Chloe.
Simon Tam of Firefly, who is too focused on his medical career (and later, helping his Brainwashed and Crazy sister) to have much luck with the opposite sex (especially Kaylee, who has a crush on him from the beginning of the show). This leads to In Vino Veritas.
Chandler lampshades this trope when he's transferred to Tulsa and his colleague unexpectedly tries to seduce him.
Chandler: Whoa-ho, back off, Missy! Wendy: ...Missy? Chandler: I don't know; I'm not used to girls making passes at me! ...Wait a minute... am I sexy in Oklahoma? Wendy: You are to me...
Being Chandler (genuinely not a chick magnet and totally crazy about his wife Monica), he instantly turns her down.
Angel turned out to be this trope in his own show. Justified because before meeting Buffy he spend one hundred years as drunk homeless guy and a century before that as soulless demon guy. And he doesn't have a reflection.
Poor boy genius Spencer Reid of Criminal Minds is like this. In one episode, he gets hit on and kissed by a movie star he is protecting, but writes it off as "transference". Later, while questioning witnesses to a crime, Hotch laments that they didn't get any information, but mentions that Reid was "propositioned by every prostitute we talked to".
Reid:[regarding his odd interests] Do you think that's why I can't get a date? Elle: Have you ever asked a girl out? Reid: ... no. Elle: That's why you can't get a date.
This trope is Played With in Season 2 with Blaine, the cute, openly gay prep school boy that Kurt has a crush on from minute one that he sees him. It's seems fairly clear that something's going to happen with them — they go every where together, Blaine has Kurt's coffee order memorized, they sing an incredibly flirty duet of "Baby It's Cold Outside"... Only to find out that Blaine honestly had no clue that Kurt had a crush on him, has never had a boyfriend before, only really been on one date with a guy who was really just a friend which ended up with him being beaten up by some guys for daring to go on a date, and so, because of his inexperience, really doesn't know the signs of someone showing romantic interest in him. This cluelessness is finally subverted by hearing Kurt sing Blackbird by The Beatles while in mourning for a pet canary. It Makes Sense in Context and is absolutely adorable!
Taken to the next level with Coach Beiste, who has a huge crush on a college football recruiter but cannot fathom him being attracted to her. His many attempts to ask her out or otherwise show interest are completely rebuffed because she has no clue that's what they are.
Stefan from The Vampire Diaries. Stefan attracted so much female attention when he first arrived at school but he was completely oblivious to all of the attention and brushed all of the girls off.
Averted in Sherlock; while Sherlock dismisses the idea of love, he is fully aware that women find him quite attractive, and was once shown flirting with Molly in order to manipulate her.
King's Quest's Alexander is a gentlemanly Tall, Dark and HandsomePrince Charming, who is often described as good-looking or even beautiful, and frequently has women (even non-human ones) gushing over/flirting with him. But he reacts to the attention with genuine embarrassment, bewilderment, and/or self-depreciation, as while he recognizes their interest he doesn't understand why, as he doesn't think he's anything special. And when he falls in love himself, he worries incessantly that the girl won't find him attractive/appealing.
Tatsuya Suou. The boy is absolutely oblivious to the affections of his childhood friend Lisa Silverman — who he sees more as a Clingy Jealous Girl. His cop brother's Katsuya not exempt from this, either. This even while they are both head over heels with MayaAmano. Word of God confirms that his canon love interest is the very male Jun. It's part this, part he's simply not interested in Lisa like that.
How dense is Katsuya? One time, on Valentine's Day, a female cop gave him some chocolate. In his capacity as an amateur chef, he spent a while telling her everything that was wrong with the chocolate, from texture to flavor, and asking why he was getting it, since it isn't his birthday.
When Link isn't depicted as a flat-out Chaste Hero, he's sometimes depicted as being receptive of female attention but unable to detect any sort of romantic element in it (even though said element is painfully obvious to the player).
Justified in the case of Ocarina of Time Link, since he's a kid. A kid who grew up with no adults around at all. No parents, no nothing. Taken a little further in the manga version, where Ruto outright proposes to him and he doesn't know what 'engagement' means. And he never really got the chance to learn about romance when he got older, given that he was in stasis..
So far, the only real subversion is the Link of Skyward Sword who, while still a Heroic Mime, seems to have a much closer and personal relationship with Zelda than any other Link has had with any girl. Rescuing Zelda is his main goal rather than just saving the world.
Shenmue: Ryo Hazuki blows all other competition out of the water in this regard. He could practically receive a concussion from all the girls beating him over the head with their attraction to him, and he just. Doesn't. Get it. Nor does heeven give a damnin the first place.
From Ace Attorney we have Miles Edgeworth, the handsome, smart, rich man who has many many girls falling for his charms and class... that he is completely unaware of. Even Maya comments on it at one point. Sadly, the only woman he does notice is the rather horrifying, age unknown, Wendy Oldbag. He has to refrain from bolting from the courthouse whenever she's a witness and absolutely loathes the nickname 'Edgey-Poo' that she's given him. Poor guy...
In Girl Genius, Moloch possibly has some excuse in that he wasn't this trope before he Took a Level in Badass as Agatha's head minion, and indeed had a hopeless crush on one of the three women now interested in him, but he still misses some obvious clues.
Gary, one of the protagonists of Ménage ā 3, is completely clueless about the effects that he increasingly has on women as the comic continues. This is nominally justified by his unhappy and repressive religious upbringing, but mostly it's just because he's an oblivious (but adorkable) geek who gains a peculiar but justified reputation as an oral sex master. The whole thing was maybe turned Up to Eleven when a rather scary dominatrix provisionally identified him as "the perfect sub".
Donald Duck: Although in his youth, he was a bit of a Casanova, now he seems to have eyes only for his girlfriend, Daisy. But, in one cartoon, "Double Date Don", Daisy's neighbor Clara Cluck falls in love with him, with him mostly trying to fend her off and finish building Daisy a brick wall. This seems to happen in a few other cartoons as well. And in the comics, especially Double Duck and Paperinik New Adventures (more prominently in PK2) Agent Kay K and his friend's love interest, Stella, from their respective comic both flirt with him a little or praise him. And he doesn't quite know what to do with the attention.