Sexy Man, Instant Harem

Often, the Casanova emits an aura of sex appeal. This aura is such a powerful force of attraction that at times, it seems like women are literally incapable of extricating themselves from him. They lose all sense of shame, crawl all over him, and are outright ecstatic if he pays any individual attention to them. The harem won't even mind the fact that he's dealing with the affections of several women at once, and hardly even views them as distinguishable.

Well, that last part is sort of forgiveable. Because the harem in this context isn't distinguishable. The vast majority of the time, the women in this harem are characters who are irrelevant to the plot at large. Heck, they'll be lucky if they even get names. Their purpose isn't to actually do anything except show that the guy in question is meant to be lusted after. Bear in mind that they'll usually ignore all of his dialogue with other characters even if he's talking about them.

Note that most women who are either main cast or supporting cast will usually be immune to this aura. This is probably due in part to the fact that it's very, very difficult to build a real, self-respecting character out of someone who feels no shame about openly lusting after a character whose main defining trait is his sex appeal.

See also: Chick Magnet, Even the Guys Want Him, Kavorka Man, Hello Nurse, Instant Fanclub. Contrast Unwanted Harem.

Anime and Manga

 * Girls tend to behave this way around Kiryuu Touga in Revolutionary Girl Utena. Including, at one point, . Although that was a misunderstanding. ... Mostly.
 * Akio, who appears later in the series as the main antagonist, has a much stronger (and creepier) influence. Case in point? His Sexy Man Instant Harem includes Touga.
 * The only thing in the series that seems to get more action than Akio is his CAR.
 * Hiroshi Abe in GTO: The Early Years. Once his character is established, a random woman or harem can be seen in nearly all of his appearances.
 * Averted with Makoto: He has several girlfriends, but has to be careful to keep them all a secret from one another.
 * Duke Devlin from Yu-Gi-Oh has this immediate impact on the school environment once he appears. For extra implausibility points, he pulls this off with card tricks. Lucky for him card games in Yu-Gi-Oh is Serious Business.
 * Lampshaded in Yu-Gi-Oh the Abridged Series, where sexy theme music plays every time he opens his mouth -- which the other characters find annoying.
 * In Ragnarok Detective Loki, or whatever we call it today, Loki's "true unsealed" form seems to have this effect on basically anyone. Even the female protagonist seems affected, and he's got a literal Instant Fanclub following him all over the place with heart-shaped eyes.
 * Mahou Sensei Negima: Everyone is Shotacon for Negi Springfield, so he's gotten this on occasion. It gets even worse when Asuna force feeds him his own Love Potion because she doesn't think it will work. It does. Though oddly not on her.
 * Then he breaks out the magic aging pills, turns into a Bishounen, and pretty much instantly acquires a fan club.
 * Kotaro also gets quite a warm reception from most girls when he uses the aging pills.
 * Even Fate Averruncus is jumping on the bandwagon in recent chapters, and he started off with five of them.
 * Hani already had a fan-club before joining the Ouran High School Host Club. Tamaki and the twins also seem to attract a great deal of fangirls. Even Haruhi has extreme Chick Magnet powers despite lacking the 'man' part of this trope, even to those who know. Also at least a few guys, who tend to feel a bit uncomfortable about it.
 * The commentaries for Ouran even point out the bit about the fangirls not having names, apparently they keep track of recurring fangirls by the formula - "twins girl, blond".
 * Many of the males of Fruits Basket have girls fall in Love At First Sight, but certain characters, especially Yuki, but to a lesser extent, Momiji and Aya, inspire drooling fangirls to follow him and swear to protect him from anything, ESPECIALLY other girls.
 * D Gray Man: General Cross Marian has this effect on women. As Allen Walker unwittingly demonstrates, the mere act of talking about him causes nearby women to swoon with what can only be explained as a gender-flipped Dulcinea-Effect.
 * Way too many people at Kyouhei's school in The Wallflower seem to be entirely and unhealthily devoted to the four bishies.
 * Gary from Pokémon has a band of attractive, short-skirted cheerleaders who follow him around in a convertible. This becomes a little more creepy when you consider that he's about ten years old.
 * Kongoh Bancho tends to subvert this pretty hard when it shows up. The first time occurs with Oyanana as an expression of how influential he is at school as the son of the school's chairman. After he's humbled by his encounters with the main character and stops relying on this influence, his "friends" all end up turning on him.  The other time this trope shows up, "White Rose" Bancho has a harem of beautiful young women as his underlings.
 * Durarara's Rokujo Chikage is rarely seen without a number of women hanging off of him.

Comics

 * Skywise in Elf Quest is the trope's poster boy for the series, having a few girlfriends (and a boyfriend or two) in every tribe. It seems the only thing he has to do to get the girls is to show up. And then he ends up in a long-term relationship with the series' equivalent of a goddess.
 * There's a rarely recurring pin that Jughead has in Archie comics that not only draws every woman not related to him (we hope) to him with insatiable lust, but it also makes the chronic girl-hater actually love the attention. Another one-shot comic has Reggie claim that this happened to him on vacation, with various nationalities of bimbos featured.
 * In Marvel Star Wars, Luke Skywalker has this effect on Zeltrons. They actively pursue him, and the first time he ended up surrounded by them he ran away and was alarmed whenever someone propositioned him. Later he matures and becomes composed enough to be "used to it", but he still tries to get away when it's not too rude to do so. The Zeltron hat is Ethical Sluthood, and they're attracted to novelty in general... but the Star Wars Expanded Universe later makes it clear that they can also pick up on Force-Sensitivity and find it immensely appealing.

Commercials

 * Many, many advertisements for body spray. Character uses body spray product. Character becomes so sexy that all nearby women actually start attacking him to get after the sexy. At this point, this is used so much that it might as well be Brand X.
 * Brilliantly self-parodied in the Hai Karate ads of the 70s, where the guy tries to fight off the girls using karate and Hilarity Ensues.
 * Another '70s ad, for a cologne called "Bacchus," pretended that this was the real secret of the Roman army's victories: they arranged to splash the stuff on the men of enemy towns, who are then mobbed by their own (all very beautiful) womenfolk. "Because when a man is irresistible to women, he has more interesting things to do than fight a war."
 * Axe body spray probably takes the crown for this one, implying that it can render bathing unnecessary, and still drive women into a sexual frenzy. Sadly, many users believe it, if the smell on most college campuses is any indication.
 * College? Try middle school.
 * Parodied rather amusingly in a new Spec Savers advert.
 * Another Axe commercial shows women being turned on by their pots and pans, which (we discover) are made from recycled Axe spray cans.

Film

 * In Michael, John Travolta's character has this power over most of the women in the film -- the sole exception being Dorothy, the female lead. Frank asks Dorothy at one point just what it is that women see in the angel. She doesn't have a clue. Michael Lampshades the trope by claiming that he put a "block" on Dorothy. But Michael is an angel, so it's not out of keeping for him to have magical powers. This is presumably the source of his power over women, and how he can arbitrarily "block" Dorothy
 * In Good Luck Chuck, the main character is "cursed" with the ability to have any woman who has sex with him find true love within a few days. The reason the word is in quotation marks is because apparently in this universe, women are so desperate for true love that they'll start throwing themselves at Chuck without abandon based solely on the Internet superstition that they'll find true love afterwards.
 * To elaborate, his secretary says that the rumor about his curse has yet to be disproved (a whole article about the "Dentist who you'll want a drill from", he himself made a comment about how he always ends up invited to his ex-girlfriends' weddings. The main ones SPREADING the rumor are his happily married exes. The main reason that the woman are throwing themselves at him are because for all intents and purposes, they really will find true love after shagging him.
 * In A Sound of Thunder (the movie, not the story), Travis is bet upon by his co-workers to bed a woman who they are working for that day. He succeeds without even doing anything -- she wanted him so badly that she convinced the doorman she was his cousin and went up to his apartment butt-naked for the chance to have sex with him. A later dialogue between Travis and the doorman implies that women apparently do this all the time.
 * This was a common device in old musical comedies, since it made a good excuse to show off the Chorus Girls.

Live-Action TV

 * The "Bewitched, Bothered and Bewildered" episode of Buffy the Vampire Slayer pretty much epitomizes this trope, though in that particular case it is magic-induced.
 * Happy Days: The Fonz can get a whole herd of woman to flock to his side by simply snapping his fingers.
 * An Outtake showed the guys of the show mocking this characteristic by going in place of the girls after the finger snap.
 * Well, are talking about The Fonz here, or at least the Flanderized Fonzie; before this, he was just a loser-mechanic who scored the lowest female trash in Milwaukee.
 * Gossip Girl's Chuck Bass. If you can get past the Narm, that is.
 * Gaius Baltar gets one in Season 4 of Battlestar Galactica.

Real Life

 * Truth in Television. For Hugh Hefner anyway. The ability of a man to do this outside of the Playboy Mansion has yet to be demonstrated, though.
 * It's speculated that it's more about Hef's unfathomable wealth and connections than it is his raw sexuality; which, at this point, simply has to be running on fumes. (And a little blue pill).
 * Six of one, seven of the other. There's a theory that old men who can provide are more attractive than young men who can do as well; any young man can provide stamina and vigor, but an old dude needs to be really fit to do as well, and thus is a better mate.

Video Games

 * Al-Cid Margrace in both Final Fantasy XII and Final Fantasy Tactics a 2. Interestingly, in A2, female Hume NPCs are rare, so he's mostly surrounded by Viera and Gria.

Web Comics

 * Commander Kitty dreams of being one, as pictured above.
 * Count Vinny from Erfworld summons some Archons with a snap of his fingers Here.

Western Animation

 * Gaston in Disney's Beauty and The Beast. His fangirls appear to be identical triplets.
 * Never quite played straight in Disney's Aladdin. The chorus girls start out mockingly describing Aladdin's charm as a street urchin, and mostly seem to praise him as Prince Ali because of Genie's magic. Their counterpoint adoration of him during the "Prince Ali" song is awesome, regardless.
 * Happens to Kuzco in an episode of The Emperors New School when he drinks a potion that makes every girl see him as a hunk... it does not turn out well.