A list of Western animated shows in which characters have unusual hair colors.
Taken to an extreme with Doug, which not only has a rainbow of hair colors, but skin colors as well. Doug's best friend Patty is a Dark-Skinned Blond, and his other best friend Skeeter has blue skin.
Ignoring the yellow skin, the characters of The Simpsons include some naturally blue-haired characters such as Marge and Milhouse's family. There are even some purple-haired people such as Patti and Selma.
There are also characters with green hair (Krusty, Sideshow Mel) and maroon hair (Sideshow Bob).
Marge may have been naturally blue-haired in her younger years, but everyone knows that, these days, she dyes it with Blue #52 (or is it Blue #56?). Also subverted with Patti and Selma. Their true hair colors were hidden under smoke and ash.
Chief Wiggum also has blue hair, but it was black in early episodes.
and the "Blue-haired Lawyer"
When Waylon Smithers was an African-American in the episode "Homer's Odyssey," he also had blue hair.
Turanga Leela from Futurama has purple hair, though it might be justified. She is a mutant.
Leela's mother has purple hair and her father has blue/gray hair.
Igner also has pink hair.
Mayor McDaniels from South Park has turquoise hair, while Nurse Gollum had pink hair. While most characters' hair is colored within the plausible range, there were occasions where background characters would sometimes be given bright blue or purple hair.
In Gargoyles, Elisa Maza has a defined shade of dark blue hair, despite most other characters having more realistic tones of hair color.
Technically, it's blue-black.
For no reason whatsoever, Tommy's father in Rugrats has purple hair. In the All Grown Up! spin-off, Tommy inherits his father's unnatural hair color, suggesting that it's actually genetic.
The same can be said with Didi's pink hair that Dil inherits.
Most of the human characters in Phineas and Ferb have plausible hair colors, except for Ferb, who has green hair.
Also, most animals are colored somewhat like they are in real life, except platypi, which are all colored bluish-green.
Except the stuffed one in the museum at the end of the chariot race, which is brown
Jem: one could argue most of the characters dye their hair, since they're all rockstars, but a flashback to the main characters' childhoods reveals that, with the obvious exception of Jem (being a hologram and all), all the kids had blue, purple, and pastel red hair even when they were kids.
Aelita from Code Lyoko has natural pink hair both in her Lyoko avatar and in the real world. She inherited it from her mother, who is shown in flashbacks to sport the same hair color. It stands out as the rest of the cast has a normal range of hair colors for French kids (assuming Odd's purple spot is permanently dyed).
Well, most of the rest of the cast. William's mother has green hair, as well as a DJ girl prospect in the episode "Crash Course". And Chris Moralès has white hair.
Odd's mother has mauve hair.
Many characters on Invader Zim have oddly-colored hair.
Interestingly, every significant female character seems to have either blue or purple hair — Gaz, Tak in her human disguise, even Zita and Gretchen. The only exceptions are hairless aliens and characters too small to really care about.
Most fairies on The Fairly OddParents have weird hair colors: Wanda has pink, Cosmo green, Poof purple, and Mama Cosma blue.
Danny Phantom from Danny Phantom has this going on. In human form, his hair is black, but when he "goes ghost", it turns white — and glows, apparently. And some of the ghosts have strange hair colors — Ember's hair is blue (and on fire), Kitty's is green, and Technus's is also white. Otherwise, it's a normal range. (The series does suffer from Technicolor Eyes, though. There are no characters with brown eyes. Even the African-Americans are green-eyed...which really doesn't make sense, but hey.)
Ever heard of Cape Verde?
Frida of El Tigre has bright blue hair. So does her father and her unseen grandmother, implying that it is genetic. That, or certain members of the Suarez family must dye their hair blue.
In Trollz, most of the characters have oddly-colored hair. Amethyst has pink, Sapphire has blue, Onyx has purple, Coal has green...Oddly enough, Ruby's hair, fire-engine red, is stated once to be dyed. Her natural color is brown.
In Total Drama World Tour, Sierra has completely violet hair, it's unknown whether it's "real" or dyed. Gwen and Duncan also have teal and green respectively, but it's dyed.
Max also has purple hair (and oddly grayish skin), again with no real explanation.
In KaBlam!, Henry has green hair, June has sky blue, and Loopy has robin's egg blue.
Rejected Nickelodeon pilot The Modifyers has Agent Xero with pink hair as her normal look and blue hair for her Perky Goth alternate identity Lacey Shadows
In Hi Hi Puffy Amiyumi, a particularly bizarre case, wherein one character has razor-cut blue hair and the other cottony pink hair (the latter also has anti-gravity pigtail-like spheres of hair above her head). The bizarre part is that the characters are supposed to represent two actual people, both of whomnote typically sport long, wavy black/brown hair.
In Team Umizoomi, We have Geo and the Blue Mermaid, who both have blue hair.
As Soar Loser in Skysurfer Strike Force, Brad Wright dawns a lime green wig. Bioborg, Dr. Five Eyes also has lime green hair.
Mara in TRON: Uprising has light blue hair; this is notable because almost every other program in the Grid has black, dark brown, or grey hair.
In The Secret Show, Professor Professor has green hair, Special Agent Ray has blue hair, and Doctor Doctor has blue hair and blue skin.
On Strawberry Shortcake's Berry Bitty Adventures, only Orange Blossom and Huckleberry Pie have realistic hair colors (dark brown and medium brown respectively). Strawberry gives "redhead" a whole new meaning, and despite Lemon's blonde moments, her hair is definitively yellow. Cherry's hair is a deep purple and occasionally sparkles. Blueberry, Plum, and Raspberry's hair colors can't be found anywhere outside a bottle in the real world.
Many of the Sugar Rush racers have odd hair colours, as befits their confectionery themes. For example, Minty Zaki has green hair; Snowanna Rainbeau has a rainbow-coloured afro.
Teen Titans has the green-haired (and skinned) Beast Boy and the violet-haired Raven as part of the main cast. In season 5, we're introduced to Kole, who has bright pink hairnote Although an animation error in "Titans Together" would depict her with orange hair, which she had in her early concept art and in the original comics. Jinx is a villain example, with her hair also being pink.
Five, the fifth most-dangerous human being on Earth, from Generator Rex has pink hair.
The Duke from Gawayn has naturally purple hair, his mother too.
Played straight, Lampshaded, and Averted in Pepper Ann. Pepper Ann dyes her hair green, in which her friends are indifferent about, causing Pepper Ann to call Milo out on having Blue hair, which he admits his hair is so naturally black it has a blue tint.