Peter Parker (a.k.a. Spider-Man). He was married to one of the most beautiful women in the Marvel Universe (before Executive Meddling kicked in). And before MJ, he dated Gwen Stacy and the Black Cat. This despite him being a poor nebbish nerd. His friend the Human Torch even called him on it, as did the Chameleon while impersonating him ("Does Parker know anyone who isn't a stunningly beautiful woman?").
Jennifer Lopez' titular character in The Wedding Planner, who is depicted as so lonely that she's willing to settle for marrying a man she doesn't love to save herself from spinsterhood. This is Jennifer Lopez we're talking about. Hell, her fiance could count too. Sure, he's no Matthew McConaughey, but he's hardly so ugly that he would need to settle for a woman who doesn't love him just so he won't be alone.
Steve Carell's lead in The 40-Year-Old Virgin has numerous awkward dates with very attractive women, but ultimately it's an aversion. The friends who view Andy as this all have love lives at least as screwed up as his, arguably more so, and he comes off as by far the most mature and level-headed in his attitude to sex; instead of Wangsting about never getting laid, he's made his peace with bachelorhood and got on with his life.
Tim from About Time is handsome enough, but he is incredibly awkward. Luckily time-travelling fixes that, as with planning and forethought he can be pretty charming.
Harry Dresden. The man's friends, co-workers, and magical spirit servants mock his lackluster love life. His love life actually isn't all that great - the books, 11 so far, each take place about a year or so apart, so he's had two girlfriends in about 11 years - but it's not all that horrible. Over the course of the series he has been in two committed relationships so far (one was The Mole, but it wasn't her fault and they're still friends) with very attractive women, plus one paper-thin Will They or Won't They?, one at least somewhat attractive lover in his backstory, and probably dozens of women who have thrown themselves at him only for him to turn them down. His love life isn't that great only because Harry has a Dark and Troubled Past and a tendency to place Honor Before Reason, not because he's really all that ugly or socially inept. In the books he's tall, dark, mysterious, probably relatively good-looking when he bothers to clean himself up, and has a sharp wit. In the TV series he was played by this guy. There's no way he couldn't get a date if he actually wanted to.
Harry's situation is made somewhat worse when you realize that neither relationship lasted very long. And he appears to have had sex once in the ~7 years between Grave Peril and Small Favor. His problem may be just that he doesn't get out enough. Seriously, does the man have any friends he didn't meet through his working life?
A large factor in this is that he's, by his own admission, a loner, very set in his ways, and a bit of a geek. He doesn't get out much, and when he does go out for a good time, it's usually to a bar where everyone there is either distantly respectful or outright afraid of him.
Harry ALSO has rather severe abandonment issues. He needs to know the relations will last. Without that, he won't dare to get into it.
Really, it's less that he's mocked for being unable to get a date so much as being unwilling to.
Sometimes. JD's problem isn't really that he that he can't get a date, but more of him not being able to have a lasting relationship (he's even worse than Elliot in this regard) like everyone else because he keeps screwing them up and ends up having to go back to "dating his laptop".
Everyone in Chuck Bartowski's life regularly acts like him getting a date of any kind, let alone one with a good-looking woman, is a minor miracle. This continues approximately through the end of the second season, despite the fact that in that space of time he dates two beautiful women and has a third one in love with him. For the most part the third season drops the facade, though.
Chandler Bing from Friends, despite being smart, good-looking and incredibly witty, is constantly knocked by himself and others for having very little in the way of a love life. Gunther and Ross also count if you really get down to it. One episode, a while after he became engaged to Monica, involved him not even being able to TALK to a women because she was beautiful, only being able to bashfully mutter a few whispers, and the characters acting like this had always been the case with him. Over the course of the past six or so seasons, Chandler had been shown successfully making some of the boldest and most hilariously charming pick-ups anywhere on television, to complete, gorgeous strangers.
There's also the matter of Monica frequently vocalizing her aggravation earlier in the series over not being able to find a boyfriend. She looked like this at the time◊. Admittedly it may be she's having trouble finding a committed relationship, as a lot of guys do hit on her (probably purely because she's so attractive) but often turn out to be jerks.
Another time, Rachel mentions that Monica "stumbles down the hall and sleeps with the first guy she finds." To be fair that was just in reference to the other holder of this Trope, Chandler, as their first night together was a drunken hook up.
The comments towards both of them being bad at relationships get even more unbelievable later in the series, when they're Happily Married and the ones who have had any healthy relationship. One episode has Joey and Ross saying that Chandler's thing is being 'bad with women'. At this point, Ross has been divorced three times and Joey has never had a relationship longer than a week and is pining after one of their other friends, while Chandler is a wonderful husband to a stunningly attractive woman who adores him.
Commandant Klink from Hogan's Heroes. The irony of it is that the women he has the most success with are actually enemy agents seeking to use him in some plot. Otherwise they would run a mile.
In Sabrina the Teenage Witch there is Miles who has continuously been referred to be beyond all hope when it came to make a positive impression on the other sex (or people in general), yet in the season 5 finale he scores with one of Josh's very attractive friends and he breaks it off with her at the end and then is seen going on a date with four Pop Stars at once.
Perhaps the most notable example is George Costanza, whose role in Seinfeld is a slow-witted, self-centered, ugly failure who repulses women and can't get them to go out with him... except for, oh, the forty or fifty gorgeous women he dated over the course of the show. He even got a model whom he suspected was bulimic. He winds up getting engaged to the attractive daughter of a rich, Upper East Side, WASPy, old money couple- Susan Ross. Even if they were evenly-matched looks-wise, it's completely far-fetched status, class and money-wise.
The worst episode for this is "The Strongbox" when George wants to break-up with a gorgeous woman because she talks to her food but she refuses to end the relationship. Finally, he sets it up so she'll catch him on a date with another gorgeous woman (who we learn had pursued George in the past but he had rejected for being "too tan") in the hopes that both women will dump him. However, they both take his infidelity in stride and announce that neither are ending their respective relationships with him and the episode ends with George having the "problem" of two hotties refusing to let him go no matter what.
Neither of whom he wants a relationship with and neither of whom will respect or accept that. It is a problem.
George was also notoriously picky. When Elaine was setting him up on a blind date, he asked multiple shallow questions about her physical attractiveness. Another episode had him breaking up with a woman who wore a wig despite wearing a toupe himself. All of these women were attractive.
Then there are episodes that seem to go the other way. In one, George claims that all he has to do to get a woman to want to date him is to see her on three separate occasions. He compares it to an advertising jingle: annoying as hell the first time, but by the third time it's stuck in your head.
Contrast Kramer, who in "The Conversion" is portrayed as being so devastatingly erotic it tempts a novice away from becoming a nun, and in "The Smelly Car", where he is able to get a lesbian to switch teams. As explanation for this, he merely says "I'm Kramer!" However, Kramer is almost never portrayed as being with women unless it's important for someone else's plot (like with Jerry's ex Gail Cunningham in "The Shoes"), and his only ongoing relationship is with Elaine's annoying roommate. George buys into it, too, describing Kramer's life thus: "Do nothing, fall ass-backwards into money, mooch food off your neighbors, and have sex without dating."
Dorothy Zbornak on The Golden Girls. The other women make fun of her for it, though, ironically, she's the only one at the end of the show who isn't single.
Worse than the George Costanza example, because Bud actually touches himself every single night out of his loneliness, always whines about being dateless, rejects girls at a higher standard than him, and still he scores repeatedly. Fail.
But unlike the George case, there is certainly a high ratio of on-screen rejections to on-screen incidents when he does score. And when he does score with an attractive female, he quite obviously feels that he's "getting lucky" rather than "this is something that happens to him all the time." And George's women are (short-term) girlfriends, while with Bud there's usually a sense that he would have just as much trouble getting a second date as he does getting a first. As for the whining, Bud's real problem is that, when Kelly wants to insult him, she uses his involuntary celibacy as her go-to first talking point.
Xander Harris, who spent most of the series in a long-term committed relationships with either Cordelia (early on) or Anya (Season 4 to the end). Also, he has a one night stand with Faith and Willow wanted him.
In the first couple of seasons it's a running joke that he does get dates - but they're all with demons disguised as women.
As of the Season 8 continuation-of-the-show comic series, Buffy confesses her love for Xander. He turns her down, since he's now in a relationship with Buffy's sister and he believes Buffy has just finally gotten to the settle-for-the-best-friend option (after "trying girls", mind you, so he might be right.) Earlier in the comic he was dating a Slayer named Renee, who was killed during a mission in Japan.
In fact, everybody on the show qualifies. Not least of which Miss Maybelline herself.
Despite the title of her show, Ugly Betty manages to have plenty of cute guys pining after her. No, she's not really ugly, but she dresses like a clown on acid.
Brian Hackett of Wings dated many beautiful women over the course of the show's run. For most of the show, he was The Casanova, but for some reason, the last couple of seasons seemed to have a lot of jokes about how he was having trouble scoring dates.
Lampshaded on Wizards of Waverly Place when Hollywood Nerd Justin asks his brother "Why does everyone think I don't date; remember the centaur, the werewolf and the Goth Girl?" The "goth girl" was in fact his established girlfriend for a several-episode arc.
Liz Lemon on 30 Rock. She's dated Jon Hamm, for goodness' sake.
The show does make it out to seem more like she doesn't have a problem finding men to date, but rather that everyone she does date turns out to be completely insane in the end so she's forced to end all her relationships.
Also, Liz has plenty of her own problems to sort out so her trust issues/childhood trauma involving posters/etc. might have some effect.
Frasier's problem is generally that he usually has trouble holding onto a girlfriend, usually due to some contrived circumstance he happens to fall into in her presence.
Ted Mosby's love life in How I Met Your Mother is generally unsatisfactory to him, and he specifies that he is looking for true love, so it'll take a lot to satisfy him. He is often teased by his friends as being awkward and shy around women. Still he has several hot women per season, (minus season II when he's in a committed relationship with Robin). And apparently the characters in this show all think it's mind-boggling for someone to go more than a few months without getting laid.
Though this could have an in-universe explanation of Future!Ted exaggerating and or misremembering.
Rachel Berry on Glee. It sort of makes sense at first since she's established as very obnoxious and the two guys she is romantically involved with in the first half of the season are in a Love Triangle over a more popular girl. But by the second half she's in the center of her own Betty and Veronica and throughout the entire series she's had a huge Stalker with a Crush in the form of a nerd who even at one point blackmails her for her panties.
Freddie on iCarly averts this, in both ways. He is never considered to be completely inept, but neither is he constantly dating insanely hot girls. 1 date was a Femme Fatale who was using him to break up their webshow, a second was with a twin he only asked out to prove that it was a trick being played by the original twin, he went to a dance with a wizard that ended poorly, and finally a date with a girl he wasn't interested in due to being forced into a triple date. The only time he's been with a girl he really likes, it's Carly, but he had been recently hit by a truck and was stuck in bed and then hobbling around on crutches. He also ended their brief relationship because he was worried Carly only liked him because he saved her from the truck.
Leonard from The Big Bang Theory, though a lot of this comes from his experience before he became friends with the pretty Girl Next Door who gave him a lot more confidence. It was said the only girl of real significance in his life (not counting minor flings) before Penny came around was Joyce Kim, later revealed to have been a North Korean spy pushing him for government secrets. The few times he is seen in a social situation he is shown to be shy and awkward, but starting in the second season he briefly dated Leslie Winkle and Stephanie Barrett, dated Penny for the majority of the third season and had a long term relationship with Priya Koothrapali that crossed the fourth and fifth seasons. In between those girls, though, it's clear that he doesn't have that great of a social life.
In a bit of character insight, Leonard has been consistently shown as very shy in public situations and on a friend date with Penny she suggested he talk to some girls and his response was "They're in a group, I'm scared..." Upon returning to the scene Leonard had actually started talking with one of the girls and if he didn't get into an argument with Penny (scaring her off with their Like an Old Married Couple fight) it seemed to be a pleasant conversation.
Timothy McGee from NCIS, who, while being a geek, manages to get quite a few dates, and still is told that he needs to get out more.
Alan on Two and a Half Men is often depicted as a pathetic loser yet he's dated a number of attractive women and was even married to a couple of them.
On Amen, Thelma's constant whining about her lack of a social life and Christmas Cake status is undermined by the fact that she actually dates a decent amount of men, several of whom wanted to marry her, all before finally snagging the handsome Reverend that she's been pining after since the show's first episode.
Spencer Reid from Criminal Minds. When the Maeve Donovan arc began in Season 8, the show's characters- most notably Derek Morgan- seem to make a big deal that he's managed to win a girl's heart, as if it's some kind of a shock for Reid to have a girlfriend. The writers didn't help much either, since "Reid gets a girlfriend" was a selling point for Season 8, believing the audience would be surprised at this development too. This despite the fact that Reid, on screen, has been on more dates than Morgan, has had two on-screen kisses and had been the subject of an early seasons Running Gag that Reid often mistakes the flirting of women to mean something else.
Davan Macintire, main character of Something Positive. Despite numerous characters, himself included, referring to him as ugly and a loser, a fair number of women have expressed interest him and he's had sex with more than a few of them. On the flip side, most of his relationships, potential and otherwise, tend to end badly.
Indeed, near the beginning of the strip one ex is able to describe herself as "the one who didn't cheat on him" (she suddenly left town instead). To be fair, now she would have to share that title with Branwen.
Marten of Questionable Content, a supposedly awkward music nerd who has had at least two attractive girlfriends. Something of a subversion in that he only acts this way because he's often oblivious of people's attraction to him.
Torg from Sluggy Freelance is, in Bun-Bun's words, a "nerd boy" who's supposed to be relatively unlucky with the ladies. Except, y'know, for Valerie, Angela, Oasis, Alt-Zoe, and (eventually) Prime-Zoe all falling for him. Justified since at least two (possibly three) of those women were just using Torg as a stand-in for previous Love Interests who had died, and another is only in love with him because she's been Brainwashed to do so.
Don't forget that radiator woman from the radiator planet.
Fry, that's a radiator.
...is there a burn ward within ten feet of here?
Kim Possible has Ron Stoppable who's overly concerned with social rankings and considered a loser by his school peers. Yet he seems insanely popular among girls - notably Yori and Kim (the latter of whom he later does date), along with Zita, and a crush by another cheerleader. Not to mention a handful of episodes where he gets involved with Bonnie. Kim herself dates little, despite being a knockout, which she attributes to her crime-fighting lifestyle and type-A drive.
Kim: "I'm weirding guys out! They see me on TV, round housing some goon out a window... It's a vivid image."
Moe Syzlak, Selma Bouvier, Comic Book Guy, Milhouse van Houten, and Principal Seymour Skinner on The Simpsons.
Moe got 600 no's in 1.8 seconds. All the others except Skinner haven't had much better luck. Edna Crabapple used to be portrayed as unable to get a date, but now she's promiscuous.
Though it deserves saying that dating and having sex aren't mutually-inclusive.
Bart has an amazing luck with girls, as he has dated and almost married at least a dozen girls. The trouble is he can't keep a steady relationship with any of them.
Jay Sherman from The Critic- a balding, short, fat, apparently annoying and once divorced movie critic would probably do a lot worse in the real world. Although he still does manage to date a psycho fan and his near-mummified makeup artist, Jay doesn't seem to have problems scoring with beautiful women.
Meg Griffin on Family Guy. She's very unpopular in the later seasons of the show, yet manages to hook up with/date at least: Doug (Prick Up Your Ears), the nudist neighbor she liked, Mayor Adam West, Kevin Swanson, Michael, a medical student, Anthony (Go, Stewie, Go) as well as being pursued by Neil Goldman and losing her virginity on live national television to Jimmy Fallon during the opening of Saturday Night Live. And when a cute, popular lesbian thinks she has a chance with Meg, she's so excited she immediately strips. In-universe other characters react to Meg as if she were the elephant man with leprosy, but she looks pretty much exactly like a slightly shorter, brown-haired version of Lois, who in-universe is pretty much uniformly considered to be hot.
On that same note, Chris has also had a few attractive girlfriends, despite his less than flattering traits. He reasons if his dad could get his mom, there must be hope for him yet.
Steve Smith from American Dad!, much like his counterparts from Family Guy. Despite constantly being described as a perpetually awkward virgin loser, Steve has had multiple hookups and opportunities to lose his virginity to very attractive girls, much more than most 14 year old boys in real life could ever hope to. For the record, according to the American Dad wiki, he has had 17 different love interests. His equally awkward best friend Snot qualifies as well.