In the Acorna Series, the title character has white hair and is a human-unicorn hybrid, with healing and other magical powers through her horn, though the whiteness of her hair stems for her people's tendency to go white after spending large amounts of time in space.
Akata Witch: As an albino with the gift of magic, Sunny has white hair and an innate ability to shift her body between the material and Spirit Worlds. Other physical traits are associated with different magical talents.
The protagonist of the wuxia novel The Bride with White Hair by Liang Yusheng. There is The Film of the Book, too.
Ramandu's platinum blonde haired daughter from The Chronicles of Narnia, who is actually a star.
In the Chronicles of the Kencyrath, white hair is a common but not universal trait of the Shanir — individuals born touched by the power of the Kencyrath's Three-Faced God, and therefore regarded with suspicion. Notable examples include Kindrie, Randiroc, and Adric, Lord Ardeth, who sensibly dyed his hair brown in his youth to hide his Shanir status.
The entire Marat race in Jim Butcher's other series, Codex Alera, tend to have white hair so a lot of them qualify as either this or White Hair, Black Heart. Kitai is the most prominent example, though there are several much less significant female Marat who are also this trope.
Brandon Sanderson's The Cosmere has Hoid, a recurring character across most of the books, in various times and across many planets. He was present at the Shattering of Adonalsium many thousands of years ago but refused a Shard, is nigh-unkillable, and appears to be collecting the powers from as many magic systems as he can. Thankfully he appears to be benevolent, and works with the heroes directly or indirectly in many of his appearances, though he has stated that he would let worlds burn if it helped him achieve his as-yet-unknown goals, though not without regret. Word of Brandon is that he was not born with his white hair, and it maybe be related to his one-time holding of a Dawnshard.
The warlock Malcolm Fade is a half-demon, like all warlocks and witches, and has powerful magic. And he has white hair.
Helen Blackthorn is the daughter of a shadowhunter and a fairy. And like her fairy mother, she has light blonde hair. These are so light blonde that they look almost white.
The Sartan have a slight variation on this — they're all (with a very few exceptions like Balthazar) born with white hair, but when they hit puberty it turns dark only at the tips. Their rivals the Patryns are the opposite — they're born with dark hair that turns white at the tips at puberty.
The human wizardess Iridal was originally blonde, but her hair turned white at a young age. When combined with her constantly changing eyes and penchant for white and silver clothing, it gives her a very ethereal appearance.
The Moonwoman in Deerskin, a goddess or nature spirit, has white hair. Lissar also gains white hair after the Moonwoman heals her and takes her memories away, which makes people think she is not human, or perhaps the Moonwoman herself. Only when this spell is broken and Lissar remembers her past does her hair return to being black.
Discworld: Susan Sto-Helit has this, with one black streak; she's also a Magical Nanny and the granddaughter of Death. Her mother, Death's adopted daughter, had pure silver hair.
Sapphira Adi in the Dragonsin Our Midst sequel series Oracles of Fire has shining white hair and bright blue eyes as a result of her status as an Oracle.
The Faerie Queens and Ladies in The Dresden Files are described as beyond gorgeous and white-haired (although the Winter Lady streaks hers with dye.)
Tessa, The Host of a Fallen Angel, has white hair in her human form. Though it is not stated that this is because Tessa is a Host to Fallen Angel.
In The Folk Keeper, Corinna has silvery white hair. The hair grows at a rapid pace of two inches per day, and she also possesses a number of other supernatural talents such as requiring hardly any food and always knowing the exact time.
Sisma, the protagonist of Andre Norton's Forerunner and Forerunner: The Second Venture, has dark skin and white hair; she's a reincarnation of an ancient semi-divine being and has powers such as telepathy and the ability to alter other people's minds.
Ghost Girl (2021): Zee, who can see and speak to ghosts, has white hair.
In The Goblin Emperor white hair is common in elves, and is about the only mystical things about elves in this setting. Goblins tend to have more mundane black hair.
Jenna, from Jane Yolen's Great Alta Saga, has pure white hair and black eyes, a sign of her status as a messianic figure; she is a heroine of legend who is reincarnated every few hundred years, always with white hair from birth.
Inverted in the first couple volumes of Kat Richardson's Greywalker series — Will, the man that main character Harper begins dating in the first book, is young and has striking white hair; but he's practically the most mundane, least magic-touched character in the series. And his inability to believe or cope with magic things comes between him and Harper. Turns out not to be such an inversion when Will is transformed into a powerful magical guardian. His white hair is the feature singled out in the final vision that Harper has of him after the transformation.
Kiki in the Kiki Strike series. It wasn't really much of a plot point, but it was used to show how unusual she was.
In Kushiel's Legacy, Alcuin is a Pretty Boy with pale skin and silver-white hair. While there's nothing supernatural about it, his "otherworldly" beauty makes him very successful during his brief tenure as a courtesan and distracts people from his exceptionally keen mind — which he usually uses to collect information on the local elite.
In the Heralds of Valdemar books, using Adept-level node magic bleaches one's hair and eyes, so any young Adepts eventually become examples of this trope. All Tayledras gain bleached hair as well, due to living in Vales with Heartstones producing so much magic around them, but mages among them gain it faster; Firesong, one of the most powerful characters in the series, had his hair turn white completely by the time he was ten. The Companions are all pure white, blue-eyed Sapient Steeds, and eventually reveal that this is because they use nodes as well, to fuel their incredible speed and endurance.
Vanyel Ashkevron of the Last Herald-Mage Trilogy, despite being Firesong's ancestor and an even more powerful mage than he is, reflects in Magic's Promise that he seems to be resistant to bleaching. Each major use of Node-magic gives him more white hairs but it doesn't happen all at once until things get serious in the third book.
In The Black Swan, Odile von Rothbart has white hair. She suspects her mage father may have changed its color.
The Last Unicorn's Lady Amalthea has white hair, which makes sense, given that she's actually a unicorn that was turned into a human.
Morgaine in C. J. Cherryh's Morgaine Cycle is white-haired and beautiful due to belonging to a half-blooded ancient race.
The Neverending Story: The white-haired Childlike Empress is the immortal ruler of Phantastica, the realm of human imagination.
Nowhere Stars: Liadain starts the story as an Eerie Pale-Skinned Brunette, but Emergence quickly starts changing that as she slowly grows her magic; after defeating her first Harbinger she gains a single white streak in her hair, that multiplies with each Harbinger she defeats. Eventually, it turns completely white. She tries to pass this off as just trying out hair-dye.
Basically every female Elf in An Outcast in Another World falls into this category. The Elves of The Village almost all have white or silver hair, and Rob notes that they're all attractive no matter what their age is.
In Anne McCaffrey's The Rowan, the title character has white hair, which is also inherited by her descendants of both sexes as a white streak.
Daenerys Targaryen has silvery blond hair, as does her brother Viserys. Their deceased older brother Rhaegar and parents Aerys and Rhaella also had them, as well. Targaryens tend to have silver-blond hair and violet eyes due to their Valyrian blood, which has been maintained through the centuries with massive inbreeding. They were also The Beautiful Elite, and their rise and fall was closely associated with their control over dragons, which is ambiguously tied to the power of magic in the world. That said, a few Targaryens did not share this trait, most notably Rhaegar's children Rhaenys and Aegon, who both inherited their Dornish mother Elia Martell's dark brown hair.
By extension, other people descended from the ancient Valyrians tend to have silvery-blond hair, too. These include the Velaryons (a house currently sworn to Stannis Baratheon, they are descended from Valyrians who settled Westeros centuries before the Targaryens did), the Lysenes, and the Volantene nobility.
Yvaine from Stardust is white-haired and is a living Star.
Ash March in Sword of Shadows has very pale blonde hair, putting her right between this and hair of gold, depending on the lighting. She's also the Reach, the one human in a thousand years who can release the Endlords from their prison, and has various abilities related to that theme.
Tales from Netheredge: The mage Myr of the North has it, setting off some alarms that he may not be as human as he tries to appear. He's part human, part fey.
Oswin, the White Prince in Terra Mirum Chronicles. Alys's first hint that he isn't human is his white hair.
The Twisted Ones: The Fair Folk-like "White People" live in an Eldritch Location only loosely connected to the human world and have hair that's "not so much white as completely colorless, like mist". The ones seen are revealed to be part-human changelings who've been abducted into the otherworld, so it might overlap with Claimed by the Supernatural.
In the paranormal romance Wake Me Up Inside, Jonah is the child of a wolf-shifter and a human, which ought to be impossible due to the incompatibility of the two species. He is either a human with white-blond hair and black eyes or a white, black-eyed wolf. That odd mix of colors isn't the only unusual thing about him either; for example, he's the "true mate" of an extraordinarily powerful wolf, and the two of them survive being separated for longer than mates usually ever can.
Lady High Priestess Evelyn from White Star and the other novels in the series by Elizabeth Vaughan has white hair with a matching white dress. She says that she used to be a brunette, but one day, she pushed her Healing Hands to the limit to save a man who had been mortally wounded. She passed out, and woke up to find the man healed and her hair permanently snow white.
Asha, the title character of the The Wishing Maiden, possibly because she is at least a century old.
Adelina Amouteru, protagonist from The Young Elites by Marie Lu, has silver hair as a side-effect of her powers.
from White Star and the other novels in the series by Elizabeth Vaughan has white hair with a matching white dress. She says that she used to be a brunette, but one day, she pushed her Healing Hands to the limit to save a man who had been mortally wounded. She passed out, and woke up to find the man healed and her hair permanently snow white.
