Dangerous Sixteenth Birthday

""The gods are so using you, Percy. Do you have any idea what's in store for you if you reach your sixteenth birthday? Has Chiron even told you the prophecy?""

-, The Sea of Monsters

There may be no more unfortunate age to turn than sixteen, especially if you're female. While there are dangers inherent in simply existing, celebrating one's sixteenth birthday is one of the most obvious. Generally, this entails the manifestation of powers, possibly some Ancient Conspiracy or prophecy, and the end of a "normal" life for the character in question. Growing Up Sucks.

In all media, male examples exist too. The timing coincides with not only the time teenagers generally start being expected to act like adults, but also the impending change in demographics. Often overlaps with The Hero's Birthday.

Anime and Manga

 * Aya Mikage in Ayashi no Ceres, who first manifested the powers of the Tennyo (Celestial Maiden), Ceres, on her 16th birthday. In one of the rare examples of this trope afflicting a male, her twin brother, Aki, also begins exhibiting certain supernatual traits after this date. Essentially the whole of the Mikage family is perpetuating an Ancient Conspiracy based on these events.
 * Tiala inherits the Red Stone on her sixteenth birthday in Dragon Quest: Legend of the Hero Abel. She is kidnapped for it the same day.
 * Kannazuki no Miko: Kurusugawa Himeko and Himemiya Chikane gain their powers as the priestesses of the sun and moon on their 16th birthday, the same day that Yamato no Orochi first manifests and begins its attempt to destroy the world.
 * Yami to Boushi to Hon no Tabibito: A relatively calm use of the trope, Azuma Hatsumi (Eve), who simply disappears from any world she enters upon turning 16.
 * Devil Hunter Yohko: The title character comes into her own on her 16th birthday.
 * Yumeria: Tomokazu Mikuri finds himself thrust into the (sometimes hilarious) war in the world of dreams starting the night before his sixteenth birthday.
 * In another male example, when Yuuto Amakawa of Omamori Himari turns sixteen, the Omamori that was sealing his powers stops working, causing him to the be target of Ayakashi attacks. Enter his Samurai Catgirl bodyguard, Himari (followed shortly thereafter by the rest of the Unwanted Harem).
 * Pacifica from Scrapped Princess is destined to cause The End of the World as We Know It on her sixteenth birthday.
 * In Romeo X Juliet, Juliet discovers on her 16th birthday that she is the long-lost heir to the Capulet family, the former rulers of Neo Verona who were assassinated and usurped by the cruel Montagues.
 * When Kanon woke up Poseidon in Saint Seiya, he said it was still not his time to awaken, and took the body of a young Julian Solo to awaken himself in his Sixteenth birthday.
 * Ill Girl Shiori of Kanon.
 * In Shikabane Hime, Oori's 16th birthday is when he has to take over for Keisei.
 * Koe de Oshigoto! has an incredibly weird example where Kanna gets asked a favor by her sister on her 16th birthday, and so began her career as an eroge seiyuu.
 * Gankutsuou: Albert loses a dear friend on his 16th birthday.
 * In Black Bird, Misao becomes a "bride of prophecy" on her 16th birthday.
 * In Omamori Himari, when the main protagonist, Yuto, turns 16, the Protective Charm given to him by his grandparents weakens, causing demons to be aware of his presence. Fortunately, he's got a bodyguard who arrives just as the seal weakens and helps protect him from the demons until he's ready to defend himself.

Comic Books

 * In the DCU, Batman ruthlessly manipulated Tim Drake, the current Robin, into believing the fall of one of their friends would result in a Bad Future ten years down the line, effectively alienating Tim from everyone else.

Fairy Tales

 * Older Than Steam: In Perrault's 1697 version of Sleeping Beauty, it was on her sixteenth birthday that she was due to prick her finger and die.

Film

 * Disaster Movie pokes fun of this. Will has a sweet sixteen party the same day the world ends, even though he is 25.
 * The Slasher Flick Sweet Sixteen.
 * In Teen Witch, the main character acquires her powers on her sixteenth birthday.
 * In My Soul to Take, the Riverton Ripper returns from the grave on the collective sixteenth birthday of the seven teenagers born on the day he died.
 * While a character is celebrating their sixteenth birthday in Demons 2, they get attacked and forcibly transformed into a monster by a demon, and become the film's main antagonist.
 * In the Disney Channel movie The Thirteenth Year, the main character discovers that he was adopted and his birth mother was a mermaid when he starts gradually changing into a merman after his thirteenth birthday.

Literature

 * In the Percy Jackson and The Olympians series, there is a prophecy known to apply to whichever child of the three major gods next reaches their sixteenth birthday.  After,   In the end, however,.
 * Horrors of the Dancing Gods: Both Lampshaded and Averted: The heroine quizzes the MacGuffin Girl about her birthday before she realizes that the girl (who has been kept in hiding for nearly her entire life) probably doesn't even know her real birthdate anyway.
 * Deltora Quest (and it's anime adaptation) has Lief beginning his quest to find the seven gems to free Deltora on his sixteenth birthday.
 * Every one of the main characters in the Mindwarp series are explicitly stated to have manifested powers on their 16th birthday. Including silver blood. Which, if they had been born with, would have been rather hard not to be aware of.
 * Tales of the Five Hundred Kingdoms: A force known as "The Tradition" attempts to make people play out their lives as if they were stories, and one of the big turning points of The Tradition's power is one's sixteenth birthday. As a Princess in one of the books reflects, if you're plain, everyone will forget your birthday and you will be miserable; if you are beautiful everyone you meet will celebrate with you. How the birthday goes can determine your life's path.
 * In Gone, the kids disappear on their fifteenth birthdays.
 * Susan Cooper's The Dark Is Rising series. A variation occurs in book 2 The Dark is Rising, when Will Stanton gains his powers as an Old One (and faces supernatural foes) around the time of his 11th birthday.
 * In Scott Westerfeld's Uglies series, people get the pretty operation at 16 (though it is mentioned to the later in some cities). Of course . It is also mentioned by Tally that it was said "they could make the operation work on 15-years-old now, waiting until sixteen was just a tradition".
 * In the book XVI by Julia Kerr, sixteen is when girls get their 'XVI' tattoo and can legally have sex. Of course, that's not necessarily a good thing...

Live Action TV

 * Evie Garland of Out of This World finds out on her sixteenth birthday that she's half alien on her father's side and possesses the ability to freeze time.
 * Sabrina the Teenage Witch is first able to use her witch powers on her sixteenth birthday. Before that, she wouldn't be even allowed to know about them.
 * In Reaper, the 21st birthday is the dangerous one. The sixteenth never comes into play.
 * In Young Dracula, a vampire gains their full powers at age sixteen. Powers start semi-developing before that point, but on a vampire's sixteenth birthday they are locked in a room with the family's blood mirror and merge with a demonized reflection of themselves in said mirror, after which they are meant to lose all traces of humanity and become evil.
 * If one or both your parents made a deal with a demon called Azazel and 10 years later you're 6 months old, life will suck, but won't be half as bad as the year you turn 23. In Sammy's case, it gets even worse...

Role Playing Games

 * In Survival of the Fittest, the day of the school trip (when the abductions took place) is that of Jacob Starr's sixteenth birthday.

Video Games

 * In Final Fantasy IX, a Summoner's sixteenth birthday makes them into an easy power source for the forces of evil.
 * Dragon Quest III opens with the hero's 16th birthday -- the hero can be male or female. Since their father didn't finish his journey to vanquish the evil Baramos, the king has been waiting for the hero to come of age so that they can take up his quest.
 * Raidou Kuzunoha vs. the Soulless Army features a major character, Kaya Daidouji. Kaya is the daughter of the very wealthy Daidouji family, and despite her upbringing she is very kind towards her friends and servants. But, apparently when the girls of the family turn sixteen, a demon possesses them until they die. This troubles Kaya and so she contacts Raidou and his boss, Narumi, to help her. She quickly de-evolves into Distressed Damsel when some weird army guards in red kidnap her, thus setting Raidou on his quest.
 * In Tales of Symphonia, Colette receives the Oracle sending her on her Journey of Regeneration on her sixteenth birthday.
 * In Zelda II the Adventure of Link, on Link's 16th birthday a strange mark appeared on his left hand,, and thus the adventure begins!
 * Tsukihime has one example:
 * Inversion: in Clock Tower 3, the heroine is sent Off to Boarding School on her fifteenth birthday to prevent . Therefore, her sixteenth birthday would actually be one of the safest days of her life.
 * In Overlord: Dark Legends, Lord Gromgard was given a gauntlet as a birthday present, which gives him access to a room where his evil potential is unlocked.
 * In the ninth and tenth Fire Emblem games, the branded can safely hide among the Beorc until their aging process slows down at the age of sixteen.
 * Mass Effect: If you choose the "Colonial" background for your character, he/she is sixteen years old when his/her colony is attacked by slavers and his/her parents killed.

Web Comics

 * In Blue Yonder, Jared has been superheroing for years -- at least long enough to be quite used to being the Distressed Dude -- but he is sixteen when the Cape Busters capture his parents, and then his sister, and come after him.
 * In No Rest for The Wicked, November is sixteen when she sets out on her quest.

Western Animation

 * In Avatar: The Last Airbender, the Avatar is located at a young age and usually informed when they're sixteen. However, Aang was informed when he was twelve because the Fire Nation was coming close to an attack. Zuko is sixteen when he finally finds the Avatar, after years of search.
 * In Sequel Series, The Legend of Korra, the titular Korra also discovered her identity as the Avatar early. She began earthbending and even firebending on her own as a child, making the usual reveal an Avatar gets a moot point and ulitmately subverting this trope much like Aang did - both of them were supposed to have a dangerous sixteenth birthday, but circumstances prevented it.
 * We do get to see Aang's predecessor Roku play it straight during a flashback in the first series.
 * Teen Titans: Raven has a dangerous unnamed birthday when she was destined to become Trigon's portal to Earth. In fact the comics had entire groups of Titans gaining powers/powerups at sixteen.

Real Life

 * Upon becoming sixteen-year-olds, Brazilian citizens can become registered voters.
 * A fair number of U.S. youths take their 16th birthday to get their driver's license, so they can go out driving with their friends, no adults. Some states have seen a lot of push recently to limit privileges before 18, though.
 * At least some states require you to have had a learners permit for a year or so before taking the test, unless you're 18, though, alleviating some of the issue.