"The girl with the curls is the real vampire. I found that out when I was in the chorus. It was the blond cutie that did all the damage to the front row."
— Nita Naldi (dark-haired actress typecast as a villainess)
This is the female version of Blond Guys Are Evil. It sometimes overlaps with Evil Is Sexy.
These are blondes from societies where the hair color occurs naturally. The characterization differs when the blond hair is a clue that the character is an evil foreigner.
Often contrasted with a dark-haired heroine — as the Femme Fatale or Alpha Bitch compared to the Girl Next Door, The Vamp rather than the Damsel in Distress, the City Mouse rather than the Country Mouse.
She is not too likely to be the Dumb Blonde, but can be, with her plotting being run more on animal cunning than cleverness, and many evil blondes have exploited the Dumb Blonde stereotype.
This hair color can be dyed and often is. In the City Mouse, this is part of the luxuries of the city. For the Femme Fatale or The Vamp, it is a calculated part of her scheming. And it can, for any evil blonde, be a symbol of her deception or her lack of simplicity.
When blondes are natural, blondness does correlate with youth (and, presumably, innocence) and so is attractive. Women therefore dye their hair blond. But after a critical mass of blondes have dyed hair, it no longer correlates with youth. And it certainly doesn't correlate with innocence; the honest brunette who does not dye her hair, perhaps because she is not scheming to get a man, appears more innocent. Therefore, blond hair dye falls out of fashion and then blondes are once again mostly natural blondes and so the correlation reoccurs — restarting the cycle.
And the series plays with this and evil foreigner tropes with nearly every (non-dumb) blonde character, probably starting with blonde Ayaka's first appearance in class as the other girls (jokingly) comment that she's clearly a Alpha Bitch trying to curry favor in "the half-breed way".
Although the exact level of "evil" varies, the Contractors in Darker than Black are disproportionately blond. While most of those seen are male, there's also Brita and Amber, assuming the latter's hair isn't actually light green.
Balalaika of Black Lagoon is a ruthless Mafiya leader who, while quite affable and protective of her associates, has no real moral standards or mercy toward anyone else.
The original Terra on the Teen Titans at first seems to be a spunky new member but then turns out to be a psychotic double agent working for Deathstroke the Terminator. She betrays the Titans and tries to kill them.
Moonstone of the Masters of Evil, Thunderbolts, and the Dark Avengers in Marvel Comics.
The bullying Taffyta Muttonfudge in Wreck-It Ralph. It's later revealed that her and everyone else's memories had been erased by Turbo/King Candy. We don't see enough of her real personality to know if she's evil at heart or was a Blank Slate gone wrong.
Films — Live-Action
Basic Instinct has two evil blondes, Catherine and Roxy. Catherine is one of the most iconic blondes in cinema, and proves to be much more evil than Roxy, manipulating her for her own purposes.
She also played Velma Von Tussle in the 2007 version of Hairspray. Velma also happened to be blond.
This trope is likely the reason two adaptations of Carrie have given Alpha Bitch Chris Hargensen an Adaptation Dye-Job. The character was brunette in the book but has been played by blondes Nancy Allen and Emilie De Ravin. The actress playing her in the 2013 remake however dyed her hair brown for the role.
Rebecca De Mornay pulled a textbook example, in the 1990s classic The Hand That Rocks the Cradle, as an ice-cold, vengeful but seemingly sweet and inoffensive au pair out for the blood of the woman who got her obstetrician husband charged with sexually molesting his patients (by way of her family). Also doubles as a Bitch in Sheep's Clothing.
Heathers has two bad blondes (one of which is eventually subverted) and a bad brunette...and a heroine, who, while not actually good, is brunette.
In Little Sweetheart, there are five blondes. One's an idiot, one's neglectful, one's a bank robber cheating on his wife, one's his mistress and one is the psychotic, amoral nine year old girl who is blackmailing the previous two and is related to the other two.
Alice Wakefield in Lost Highway
In the 1983 film The Man Who Wasn't There, Morgan Hart played Amanda Worth, alias "Mr. Tendyck", a blond Woman in Black who became briefly invisible by drinking a green potion which she planned to monopolize. The film's other invisible blonde, Cindy Worth, was played by Lisa Langlois.
Subverted in The Mask. Tina starts the movie dating the bad guy and helping his plans, but is not evil on her own.
In Mean Girls, we have a good redhead [Cady] and a good brunette [Janis], a not-so-good brunette [Gretchen], a two not-so-good blondes [Regina and Karen]. Though in fairness, to call the rather sympathetic Karen actually evil is much too strong. Regina, on the other hand, embodies this trope, prior to her sort-of redemption, anyway.
Laurell K Hamilton's Anita Blake series also takes countless potshots at blond women, apparently for no reason except that Anita is a brunette. Any blond woman is immediately dismissed as weak, shallow, and both slutty and sexually frigid.
It didn't help that the author's ex-husband admitted that tall, thin blondes were his "type", and has since married a blonde.
Given how much effort she's spent portraying the character based on her ex-husband as being an utter bastard following their breakup, that's hardly coincidence.
In Tortall's Song of the Lioness, the blonde Princess Josiane of the Copper Isles, Jon's mother's hopeful betrothal for her son, is a traitor conspiring with Duke Roger to take over the kingdom.
Stephenie Meyer apparently has some issues with blond women. In the whole Twilight series, there is not a single blonde woman who is neither evil nor nasty. The most sympathetic one is Rosalie, who is depicted as being pathetically jealous, shallow, and vindictive, and who was gang-raped because she was so hot. Blond men are characterized very much the same way, so it could be said that Meyer dislikes blondes in general.
There's an episode of Charmed called "The Power of Three Blondes". It's about three criminal witches, named the Stillman Sisters, who are all blondes, and their characterization is largely built around their blondness. They are an Evil Counterpart to the Halliwell Sisters, who are all brunettes, though Paige was actually strawberry blonde at that point. Only one of the witches actually fit the trope as the other two were more Dumb Blondes who happened to be evil.
The Charmed Ones have to deal with more evil blonde witches in Billie and Christy Jenkins.
Patricia Fernández in Yo Soy Betty La Fea, although her hair is actually dyed (in fact, her nickname among the employees of Ecomoda is "La Peliteñida", the Hairbleached), and her evilness is mostly ineffectual, which seems to be a Lampshade Hanging of this trope.
Parodied along with every other trope of the genre in an episode of My Name Is Earl where Catalina writes a soap based on her life. The evil blonde is Joy.
Burn Notice has Carla, Michael's rather bloodthirsty handler. She's even described at one point as "tall, blonde, and evil." For comparison, Michael's exes are both brunettes.
Elle Bishop from Heroes is one evil blonde...but this is only because of the Company experimentation with her abilities at the hands of her own father, though she doesn't recall any of it.
Sarah Corvus from Bionic Woman, an obvious antipode to the short, immature brunet heroine.
However, Quinn does a Heel-Face Turn after becoming pregnant and getting kicked out of the Cheerios. She realizes that they were much nicer and kinder to her than her previous friends and stays with them, even standing up for them against Sue.
Similarly, Brittany is just too sweet-natured (and far too slow) to really count as evil.
While maybe not evil in the typical sense, Lily in Privileged is blonde, and is shown to steal, take drugs, and generally provide a messed-up counterpart to good girl Megan. On a smaller scale, there's Jordanna, one of the twins' school friends who, among other things, spikes Sage's drink as revenge for the twins sabotaging her party by throwing their own on the same day.
Legend of the Seeker, particularly in the second season, contrasts blond, morally ambiguous villain/antihero Cara with pure, moralistic, dark-haired Kahlan. This is also at least a partial subversion, because it turns out that Cara is a tragic figure of corrupted innocence while Kahlan becomes something of an uptight bitch.
There's also Sister Nicci, who is blond after coming Back from the Dead, and also contrasted with Kahlan in the episode "Bound". This is also something of a subversion, as Nicci has a similarDark and Troubled Past as Cara and eventually turns on the Keeper.
Vera, the only blonde in the regular cast of Queen of Swords, is a treacherous, manipulative, adulterous bitch who gets hot and bothered watching executions.
Amber on House was such a cut-throat bitch that the characters nicknamed her "Cut-throat Bitch". Then she became Wilson's girlfriend and died.
Sam on iCarly, occasionally (especially if you're Freddie)!
If a woman on NCIS has short blond hair, especially if it's dyed, you can be pretty sure she's the killer. Several episodes have had women fitting that description as the killer (in one early episode, there were two of them).
Nicole and Mary Cherry from Popular fit this trope incredibly well, particularly Nicole. Brooke was a bit of a subversion, though.
Person of Interest: Root is blonde, believe it or not. She must have dyed her hair to look like a brunette.
In Game of Thrones the discovery of Cersei's incestuous relationship with Jaime is visually depicted by Eddard Stark going through the Baratheon family tree and realising that all Robert's family are dark-haired except for his children. The implications are that blonde hair in this case is the proof that someone else must have fathered Cersei's children - someone blond.
Sally Pendrick from Murdoch Mysteries. She appears to be just a refreshingly modern woman with a shady husband. However, she's revealed to be the Big Bad of season 3. She's a criminal mastermind and was able to fool both her husband and detective Murdoch. Her husband, an Insufferable Genius with a brilliant mind was oblivious to her true nature. When asked why she do this, she says that she needs a challenge.
Lottie, the teenage serial killer of Nick Cave's song "The Curse of Millhaven": "My hair is yellow and I'm always a-combin'."
Kelly Clarkson's love rival in the "Since You Been Gone" music video. Of course she's evil because she's with Clarkson's ex-boyfriend. The trope is inverted in Clarkson's next video "Behind The Hazel Eyes" where Clarkson herself is blonde and her love rival is a definitely evil brunette.
Jacqueline Natla, Amanda Evert, and Sophia Leigh in the Tomb Raider series. Amanda reforms later on, though.
Subverted in Fire Emblem: The Sacred Stones, where Selena Fluorspar is a blonde, an enemy unit...and an incredibly sympathetic Dark Magical Girl.
The Resident Evil series has Annette Birkin and Alexia Ashford, though the former isn't so much evil as she is obsessed with getting revenge on the people who wronged her husband.
In Resident Evil 5, Jill Valentine, usually a brunette, has her hair turn blond during her Brainwashed and Crazy period, it lost all the pigment because the virus was constantly being pumped into her bloodstream.
In Kingdom Hearts, the Organization has Larxene. Kicks Sora twice, bitch-slaps Namine, and is perhaps the most outwardly evil of the Organization, with only fellow sadist Xaldin (who has black hair) rivaling her in that area, though normally stoic blue-haired Saix can outdo them both whenever he feels like it.
Subverted with Leblanc in Final Fantasy X-2. She starts off as an antagonist to YRP by trying to steal their spheres at every turn, but eventually pulls a Heel-Face Turn when she realizes her "lover", Nooj, is working to fight a greater threat, and befriends Yuna in her fight to aid him and save Spira once more.
Blonde. Sweet Lolita dress motif. A drunkard. A serial killer with a baseball bat (and alcohol for lighting it up). Batshit fuckin' insane. So numb to killing people that at least one of her opponents voices his disgust. That's Bad Girl for you.
Dead Space seems to have a thing for evil blondes (and ineffectual blondes, weak-willed blondes, mentally unstable blondes, and ineffectual, weak-willed, and mentally unstable blondes who then turn into Necromorphs).
Lucrezia Borgia plays this straight until Cesare breaks her heart and she reveals his location to Ezio.
Meredith from Dragon Age II turns homicidally insane and paranoid in Act III thanks to the influence of her new red lyrium sword. A similarly corrupted Bartrand says that "she glittered like the sun, but her heart was like ice."
Batman: The Animated Series had three: Catwoman, who mentioned at one point in a comic that she dyed her hair, Harley Quinn, who also denied being a real blonde, and Mary Louise "Baby Doll" Dahl.
There's odd inconsistency with Catwoman — her hair colour changed between seasons, and this was explained with her stopping dyeing her hair with animal-tested products, but back in the episode Tyger, Tyger, she was transformed into a Half-Human Hybrid, yet had fur the identical shade to her then-blonde hair.
May Kanker in Ed, Edd n Eddy. Though it is worth noting she is usually portrayed as the most sympathetic of the three sisters.
There is a deliberate subversion of this trope in As Told by Ginger, as while one would assume that Courtney is a Alpha Bitch, the episode "Wicked Game" showed that Courtney is probably the best friend Ginger ever had. There's also Hope Rodgers, who is a nice person too.
At the same time, the trope is technically played straight as one of Ginger's friends Dodie is blonde. Dodie is very much a Designated Hero and in the above-mentioned "Wicked Game" actively tries to sabotage Ginger's relationship with Darren. There's also the blonde and Ax-Crazy Polly Schuester.
Suzy Johnson on Phineas and Ferb, though this stands in contrast to her also-blond-but-much-nicer brother Jeremy.
Interesting case on American Dad! with the character Lindsey Coolidge, who fits this trope quite nicely and is often the Alpha Bitch of the story, yet her best friend is the incredibly unattractive and unpopular girl Jewel.
Definitely averted with Midge and Davina on My Family And Me, who are portrayed as nice and kind girls. Even Midge's cousin Eden, who's Spoiled Sweet, is not nearly as selfish or mean unlike other rich people are portrayed. Roxanne, on the other hand, kind of plays this trope quite well since she's the captain of the cheer squad and the most popular girl in school. Sometimes she can be nice and polite, but other times, she can be pret-ty nasty to some people, including the non-popular students. She's even more evil than Lacey, who's more of a Lovable Alpha Bitch.