The Cadbury's Caramel Bunny ads back during the 1980s pretty much involved every single male animal fawning over her whilst she promoted chocolate. Adding to that, in a 2009 UK-based poll she was even voted the 3rd sexiest cartoon character of all time, just behind Betty Boop and Jessica Rabbit.
Ran from Super GALS!, although it seems like the guy's reaction to her is partially because of her fiery personality and knowledge of the "gal" subculture. The only guy who doesn't seem to be (immediately) affected by her is Rei, who constantly warns his head-over-heels friend Yuya that "she's trouble." (Although the "trouble" is referring more to her hot temper than her being a Femme Fatale—in fact, she constantly rebuffs guys that want to sleep with her and is a proud virgin.) At one point in the series almost all the guys in Shibuya hold a contest for who gets to have the right to be her boyfriend. She happily claims the one who wins and breaks the hearts of all the other boys. ...Yes, in case you're wondering, she is a bit of a Canon Sue.
Mikado-sensei from To Love-Ru. A fan of stockings that uses her charm with the perverted principal and to mess with Rito (skinship anyone?). It doesn't help that some of her machines requires one to be naked.
Cool Big Sis Dr. Yamaguchi from Hajime No Ippo is a Hello Doctor case. She's a friendly and cheerful young doctor who has her own clinic, and the fact that she often wears very short miniskirts and possesses huge breasts do the rest. (Oh, and Yamaguchi's so Married to the Job that she completely fails to notice her effect on Ippo's sempais.)
Actually, she has that effect on Ippo too.
A minor character from YuYu Hakusho called Ruka fulfills this trope.
In the anime/manga Dragon Ball, during the 21st World Tournament, the third match pits a woman named Ran Fuan against a tall monk-like fellow in a turban named Namu. Ran Fuan isn't a terrible fighter, but Namu is just that much better, and one of the cards that she plays to try to throw him off his guard is to seduce him in the middle of the fight by putting on a Hello Nurse act and taking off... A couple articles of clothing.Namu's solution? He closes his eyes.
Yayoi Sanzenin, the school nurse in Happy Lesson, always has a queue of students waiting outside her office.
Yukariko Sternberg of Mai Otome had this effect on some men. Since Otomes must abstain from sex or lose their powers, this led to her canceling her contracts and eventually becoming a teacher at Garderobe.
Ranma Saotome of Ranma ½ is a hotGender Bender. Men who don't know that he's a genderbender ogle at his girl form, those who do know still ogle at his girl form, many ask for a date, some propose marraige, some kidnap him in order to forcefully propose marriage, et cetera. It doesn't hurt that he provides at least 80 percent of the Fanservice for the show either.
Aki, the school nurse in Maken-ki!. Bonus points for having a penchant to use her special powers for magical Intimate Healing.
Evangelion had Misato visiting Shinji at school once. The beautiful buxom career soldier immediately evoked this reaction from his male classmates.
Elizabeth Chandra (who later drops her first name) from J Michael Straczynski's Rising Stars had the power to be the most attractive girl possible to any man—later, when her power increases, it even works on women too.
The real tragedy of her power was that with the exception of something like a few others from the Specials, no one ever saw her. They just saw "the most beautiful woman on Earth". It's like looking at a tree, and just seeing the tree, not the branches, leaves, and texture of the bark that make it up. She and the guy who had the supposed invulnerability had been Blessed with Suck.
The Spirit: P'Gell. The first story featuring her had her warning its readers on the first page (spread out over a couch in a jaw-dropping red dress) that "this is nota story for little boys!"
For Melody of Josie and the Pussycats, the Running Gag is that she causes this reaction wherever she goes, and is too naive/dumb to notice.
There is actually a comic with the trope namer as the protagonist; Hello Nurse takes down ninjas and other evil dudes with her amazing fighting skills. It's about as awesome as you can imagine.
In the Twilight fanfic Luminosity, there’s a vampire whose power is beauty: literally. Everyone who sees her, even other women, even other vampires, are so stunned by her beauty that they will mindlessly follow her around until her self-esteem is high enough that her beauty level drops off to normal. Though, since she’s a vampire, her “normal” is still on a Hello Nurse level, just without accompanying magical compulsion.
Jessica actually played a nurse in the Disney short-film Tummy Trouble featuring Roger Rabbit and Baby Herman.
An odd case, since Roger is the one that other Toons consider a real catch.
Tina Carlyle in The Mask, reduces the civilian Jim Carrey to a gibbering wreck by asking to open a bank account, and causes his Masked alter ego to herniate his beating heart through his shirt and literally wolf-whistle.
Iaia the cookie seller from The Three Caballeros makes Donald Duck and José weak at the knees. They spend their entire trip to Bahia competing with each other (and a large crowd of men that show up) for her affections. In fact, about half the movie has Donald chasing after some Latin lady.
In Dirty Rotten Scoundrels, Janet Colgate makes her entrance as, well, this. Both con men go for her at once.... only for her to con them by the end of the movie.
From Toy Story 2, Buzz Lightyear and the gang are in Al's Toy Barn, where they stumble upon Tour Guide Barbie. Mr. Potato Head immediately begins chanting that he is a "married spud", while Hamm tells him to step aside for the single fellas.
Invoked again by Toy Story 3, when Ken meets Molly's Barbie doll for the first time, accompanied by Gary Wright's "Dream Weaver".
The Saffron Burrows character in Enigma.
Rita Hayworth played these type of characters especially in Gilda and The Loves of Carmen.
Staff Nurse Dorothy Denton (Shirley Eaton) in Carry On Nurse. Eventually got her man, Ted York.
Molly in She's Out of My League personifies this trope—her introduction is one long slow-motion montage of her walking through an airport, catching the awed attention of every man (and teenage boy) she passes. When she gets to the TSA counter, the cynical and bored Stainer suddenly perks up. Later, when she meets Kirk's family, his mother squeals with glee and everyone else just stares.
Georgette the literal Rich Bitch from Oliver & Company is this to the canine world. Just a small appearance on her balcony gets all the dogs in the neighborhood flocking to admire her.
Vesper Lynd in the 2006 version of Casino Royale has this effect on the entire casino the first time she appears in that dress. Bond intended for her to enter from behind him so his opponents would be Distracted by the Sexy. Instead she enters right in his line of sight to screw with him after an argument and distracts him as well.
Zoya, in House Of Meetings by Martin Amis. One character is sent to a gulag in Siberia because he is overheard praising America. In fact he was praising "The Americas"—the nickname he and his brother had given Zoya due to her hourglass figure.
Elli Quinn in Lois McMaster Bujold's Vorkosigan Saga. After getting her face burned off in a battle, Miles paid for the finest reconstructive surgery for her that money could buy. Though initially delighted with the results, she later came to find it to be a problem at times, when soldiers under her command made passes at her, rather than following her orders.
Lara Raith from The Dresden Files is a succubus, has used her significant...ah...assets in the past to make a name for herself in "adult" movies (see Blood Rites), and is now the power behind the throne of the White Court.
Mia in The Dark Tower series, who is a slutty ball-buster but who does gain some sympathy right before her newborn spider-baby kills her and drinks her blood.
Veelas. A "cheerleading" squad of them can make a whole mega stadium of men go wild. And then they go One-Winged Angel...
Fleur Delacour, who—guess what?—is part Veela. Lucky Bill Weasley.
Dmitri in The Brothers Karamazov can't help but speak of Grushenka's "infernal curves" dancing about in his mind, driving him insane with lust.
Rhapsody in the Symphony Of Ages series by Elizabeth Haydon. This was partly due to natural beauty, but mostly due to the fire magic from her journey through the center of the earth.
In War and Peace, Elena Kuragin, more often called Hélène (a name derived from—oh just guess!), is perhaps the most beautiful woman ever born. She's the sort of woman that makes grown men weep and young boys lock themselves in bathrooms.
Cloud Of Sparrows by Takashi Matsuoka has Emily, a Christian missionary that comes to Japan fleeing from the men in her country who apparently considered her so irresistible that she almost got raped twice. It doesn't help that she's about to marry a bible thumping guy who can't help getting aroused every time she walks by.
Despite living in a country of extremely beautiful people, everyone still manages to think that Phedre is, well, most extremely beautiful of all.
Helen of Troy is the original one, and judging by her being played by Diane Kruger in Troy, she still measures up pretty well.
Lúthien. Everyone upon her path tried to claim her, including Morgoth.
Arwen, Lúthien's great-great-great-granddaughter, was also supposed to be her exact spitting-image.
Succubi in The Case Of The Toxic Spell Dump have this quality, obviously. When a bunch of them gathered to picket city hall in protest over Angel City's new anti-vice laws, they didn't bother to bring signs, because their "arguments" were self-evident.
Several can be found in the Wheel of Time series. Morgase and Elayne often tie men's tongues, as does Berelain (though it appears she'll be meeting her match in her "Man in White" in the next novel).
Elayne's hated step-brother Galad, who's so beautiful that drooling Aes Sedai gather to watch him take off his shirt.
The nation whose women are known around the world for having this quality, and using it to their advantage in trade: Arad Doman.
The most potent example is Lanfear, however. She actually uses Illusion to tone down her beauty, and still trips up any man she talks to.
Also from Pratchett's Discworld, Sergeant Angua of the Watch. (Nobody dares to wolf-whistle at her ... especially during a full moon).
And the lovely Tawneee, a woman who was Miss April, May, and June in Girls, Giggles and Garters—a woman who has so intimidated men through her looks that the only boyfriend she can get is Corporal Nobby Nobbs of the Watch. Who later dumps her because she cannot cook.
Laurana in the Dragonlance series. The first time the Companions see her they are completely mesmerized and can do nothing but stare at her and babble on about how she is the most beautiful woman they have ever seen. Even Raistlin is affected by her beauty. Later on her Arch-Enemy, Kitiara, can do nothing but bitterly complain about how everyone raves about Laurana's beauty.
Dejah Thoris, from John Carter of Mars, is referred to as "the incomparable Dejah Thoris" for a reason.
Her daughter Tara and granddaughter Llana share this trait. Multiple men are willing to ignore Tara's personalityflaws because of her beauty, and one character who sees a figurine of Llana refuses to believe that it is of a real person, on the grounds that real women can't possibly be that beautiful.
Gloria "Ripples" Brancusi, RN, from Trapper John MD is another sympathetic example.
In Mad Men: Joan Holloway (played by Christina Hendricks), the bitchy, seductive secretary with the unbelievable body, who turns out to be both extremely bright and pragmatic enough to realize that her intelligence is going to do her exactly no good at all in the giant boys' club where she works.
Bones: According to Booth, "There isn't a guy in this country who wouldn't want to have sex with Temperance Brennan, including half the gay men." Of course, it is Emily Deschanel.
That '70s Show: Jackie's mother, Pam, played by Brooke Shields. A particularly well-executed instance, in that the male characters react to her according to their individual personalities. When the Formans invite Pam and Bob over, Eric and Hyde dress up but coyly feign ignorance about her coming over; Red acts helpful to Pam while ignoring the other guests and even Kitty, and Kelso, in his usual style, bursts through the door shouting, "What's she wearing?"
The first season of M*A*S*H had Nurse Cutler, whom Hawkeye and Trapper went to ludicrous and sometimes life-threatenening lengths to keep at the 4077.
Will And Grace has Dr. Morty, played by Nicolette Sheridan. Grace mentions to Leo she is uncomfortable with him working with her. He responds that she's not his type, to which Grace immediately retorts, "Oh, please. She's everyone's type, hell, I'd do her."
The Saturday Night Live character "Shanna" played by Kristin Wiig makes fun of this trope. She's a voluptuous secretary who speaks in a breathy Marilyn Monroe-like voice and the men in her office drool over her until she attempts to do something sexily. Instead of it being sexy it ends up being gross and weird. All the men are put off by her increasingly disgusting traits except the boss who grows more and more infatuated with her.
Cerie on ThirtyRock. She is usually oblivious to her effect on everyone. Most of her wardrobe is ultra-mini skirts and shorts, and very revealing tops, which don't help. Liz tries to get her to wear more office-appropriate clothes... and eventually gives up.
NCIS has pulled a "Hello Nurse" a few times by putting the normally rough-and-tumble Ziva into a bikini or a backless, slinky dress. But it kicks it up a notch in the episode in which Abby dresses like Marilyn Monroe, or any episode in which Abby is shown wearing mainstream business attire.
Sarah Walker on Chuck has this effect on pretty much everyone. Ellie is practically giddy when she meets Chuck's gorgeous "girlfriend" for the first time, and especially early in the series many characters don't believe Chuck could possibly be dating someone like her.
Kelly Bundy in Married... with Children. Pretty much very male on the show (except from her father and her brother) drools over her.
Dorothy of Oz: Selluriah's Witch form tends to elicit this reaction from people. Indigo is pretty much the only male in the series to witness it and not melt into a puddle on the floor. Though it's implied that this is only because he's seen it so many times it no longer has a noticeable effect on him.
Nurse Rosetta, the title character of a song from Alice Cooper's From the Inside album.
The song "Brain Damage", from Eminem's first commercial album The Slim Shady LP, gives us the line, "Teacher, teacher! Quick, I need a naked nurse!"
The music video for "As Good As I Once Was" by Toby Keith. The final scene sees Keith—playing a bar patron socked by a giant muscle man during a barroom brawl—in the back of an ambulance, tended to by a sexy female paramedic. Keith tries to pinch her behind before he ultimately passes out; the final moments of the video are seen from Keith's perspective, with the screen turning blurry before going black as he slowly loses consciousness, the medic the last thing he sees.
Stupefyin' Jones from Li'l Abner—also see Film above for the musical.
Pretty much any woman in Professional Wrestling who doesn't look masculine. Female managers and valets are known to take advantage of this by using their... assets to distract their client's opponents (and the refs), allowing their client to get the win.
Nymphs in Dungeons & Dragons are so beautiful that merely looking at them can make you go blind. Or in some editions, dead! (In some cases, looking at a clothed nymph will blind you, while looking at a nude one can kill you.) Most women require an extra step.
You can play as one in the Old World of Darkness since Appearance is an attribute measured from 1 to 5. One is ugly, two is average, three is the pinnacle of mortal beauty. You can take it up 4 (legendary) and 5 (impossibly beautiful). In Exalted, you can take this 'to ten. The sight of which would probably kill mere mortals.
The Sidhe, from Changeling: The Dreaming get 2 free dots in Appearance which means that at least they are more beautiful than an average woman and at their full potential they are, virtually, beauty goddesses.
The New World of Darkness dropped the Appearance attribute, but, seemingly, replaced it with Presence which has a similar concept but it does not refer to your physical appearance but to your allure. They do have the Striking Looks merit however.
The nurse, naturally enough, in the Doctor's Office sketch from Oh! Calcutta!.
Stupefyin' Jones in the musical version of Lil Abner, whose sex appeal is so devastating that she's classified as munitions.
Mai Shiranui from Fatal Fury, who pursues her best friend Andy Bogard relentlessly, despite him being a Chaste Hero.
Morrigan Aensland from Darkstalkers who, being a succubus, makes a living out of taking advantage of stupid men. Cat Girl Felicia also qualifies from her Stripperific appearance and added that she's an exotic battle dancer from Vegas to boot.
Marjolaine has this effect on Leliana's male teammates in the opening of the DLCLeliana's Song. Partially justified by her training as a bard.
Sheena Fujibayashi from Tales Of Symphonia, of the oblivious or unwilling to exploit it type. (It is implied she is a virgin.) In fact, she tends to get violently defensive whenever anyone (especially Zelos) starts mentioning her looks. True to trope, the only person whose attentions she wouldn't mind would be Lloyd's—who for the most part wouldn't know romance if it came along and struck him hard in the head.
To a lesser extent, RaineSage, who has a fanclub in her hometown of Iselia.
Path of Radiance: Every support conversation involving Nephenee or Lucia includes someone telling them how beautiful they are.
Honorable mention goes to Reina Mayuzumi from Trauma Center (more specifically, Under The Knife 2).
Sadly, her beauty was, in many ways, only skin deep. In fact, she turned into a crippled old lady once the GUILT she knowingly and willingly incubated in her body became active.
Litchi Faye-Ling from BlazBlue. On top of being a doctor/nurse, her assistant says everyone in Orient Town is crazy about her, and let's not even talk about how crazy Bang Shishigami is towards her. Well, judging on how she looks, who'dblame her? It helps that she's a genuinely kind person.
Mia Fey, having the advantage of a bigger bust than both Dahlia and April, gets quite a bit of this too from characters such as Larry, Gumshoe, and Victor Kudo, especially when Maya or Pearl is channeling her.
Fey at the Super Hero School Whateley Academy in the Whateley Universe. Not only possessed of the beauty of the Sidhe, but also having a Faerie glamour that (at the start of the series) she cannot turn off—though she later damps it down. Slightly.
Eric Schwartz's made-on-the-Amiga Amy the Squirrel series of animated shorts (would be web-original, but they predate the web, having been made in The Eighties) is possibly an inspiration for Minerva Mink. Amy's still around in the Sabrina Online comic.
Viewable here. (Sadly that is the original sound quality.)
Doki Can be regarded as this, is a large bust is to be taken into account
Minerva Mink and Hello Nurse from Animaniacs, the source of the trope name. (Hello Nurse herself fills the role of Hospital Hottie as well, though she doesn't have a hospital to heat up.)
A male nurse is also introduced at one point to get this reaction out of the Warner Sister, Dot, proving that this trope can indeed cross the gender barrier.
Minerva Mink is also a prime example of the cases in which the one guy who has the same effect on her that she has on men is completely uninterested.
An episode that parodied Star Trek had Not!Spock mindmeld with Wakko. The mindmeld caused Not!Spock to temporarily absorb some of Wakko's traits. When he sees Not!Uhura he immediately has this reaction.
Scarlett Johansson reportedly had this effect on the film crew the first time she walked on the set of Iron Man 2 in her Black WidowSpy Catsuit. She literally caused production to stop entirely for several minutes and the cast and crew could only stare at her.