Wing Pull

It's the endgame at last, or at least close to it. The heroes have fought past the Mooks, dealt with the Quirky Miniboss Squad, even defeated The Dragon. They've caught up to the Big Bad, and now it's time to rescue the hostage, and finally put a stop to their nemesis. There's just one problem: the Big Bad is big. Really, really big, and tall. Or, he's flying. Or piloting a Humongous Mecha. That's flying. Either way, the spot they need to reach to get to the hostage is very high up off the ground. There's no way they'd be able to reach that without flying.

Then, one of the characters steps forward. Hang on just a sec, guys, I have a sort of embarrassing secret to tell you...

A subtrope of The Reveal, with more specific revelation material: as it turns out, this particular character has had wings on his back the whole time, keeping them secret. But now they need someone who can fly, and it's up to him.

See also Winged Humanoid. Can be a heroic One-Winged Angel. Can be combined with But Your Wings Are Beautiful. This particular revelation will usually be considered a Late Arrival Spoiler in promotional art from that point on.

Examples of Wing Pull include:

Anime and Manga

In chapter 50 of Mahou Sensei Negima, Konoka is being held on the shoulder of a giant demon thing. Cue Setsuna stepping forward...

"Here it is, my true form... I'm a monster, just like them."

- Of course, everyone else (like any reasonable person on the face of this Earth) thinks that the wings are awesome.
  - Mind you, she was justified, in that in her culture, white wings (like hers) were considered bad luck, and got her exiled from her tribe.
When Saya falls from a skyscraper in Blood+, Hagi jumps off and sprouts wings to rescue her.
In Vision of Escaflowne Vaan reveals his wings while saving Hitomi from a fall. Dramatic enough, especially as Hitomi had been having prophetic dreams about a winged savior for several weeks, and was distraught about the man's true identity. Moreover, the fact that he (and almost nobody else) has wings, and why he keeps them hidden forms a major part of the overall plot.
Nico Robin in One Piece can sprout wings for five seconds. The usefulness of this is drama dependent.
In Saint Seiya, after the Wall of Lamentations dividing the Inferno from Elysium has been pierced, the Saints find themselves faced with an infinite void of warped space. Conveniently, the Bronze Cloths (that had been splashed with drops of Athena's blood at the beginning of the story) can not only protect them from the instantly-lethal dimension, but also grow wings that allow them to fly to Elysium.
Dragon Boy, the aborted original version of Dragon Ball. The hero had dragon wings that he revealed only when he was doomed.
Akira the Devilman literally pulled a pair of wings out of his back in order to stop a fall and then fight a flying demon. Since he's, well, a devilman that wasn't too much a surprise but still he never used or even demonstrated them before that moment.
Beelzebumon from Digimon Tamers sprouts a pair of black, feathery wings out his back when he goes into Blast Mode.
- A better example would be the Main character/main mon hybrid Dukemon who gains SIX angelic wings on activating his Crimson Mode.
Pokémon has a weird example where a Leafeon suddenly sprouts wings as a result of its Aerial Ace attack and teammate's Psywave attack combining. Needless to say, this can't happen in the games.
Diana, Seleção No. 11, to escape the hotel where she was. It turns out it was an illusion, but, being Juiz's work, was a really good one.

Comic Books

Happens to Hawke near the end of the original run of the comic Tellos. He suffers lethal injuries during the flight, and when he dies, he turns into... you guessed it... a giant hawk. It had been foreshadowed several times: Hawke keeping some big secret was causing real problems in his relationship with his love interest.
- Heck Angel has (pun intended) pulled this one off multiple times, when in civilian clothing.

Film

The Dark Crystal had a variation. Just as the two protagonists are falling off a cliff, the girl sprouts wings. It turns out only girls of that species have them, but since it's never mentioned before...
- ...except in some carvings you don't get all that long to look at, and it isn't really clear that the wings on some figures are actually for gliding, rather than just sartorial whimsy.
The Iron Giant doesn't find out he has boosters on his feet until he accidentally falls off a cliff and they activate automatically.
In a villainous variant, Jeepers Creepers didn't reveal that its demon/monster/alien thing had wings until it'd been shown on screen several times.

Literature

Justified with Aziraphale and Crowley at the end of Good Omens. The two characters in question are known to be an angel and demon throughout the entire story. It's only at the end when they face off against Lucifer and think they're going to die that they decide they might as well go out the way they came in.
This happens to the Karnee folks in Holly Lisle's Matrin books, who also have to fall off a mountain or a building or something in order to fly.

Live Action TV

Done in one of the Kamen Rider W movie by Kamen Rider W, in his Cyclone Joker Gold Xtreme mode. It's only for a few minutes, enough time to to stop falling off Fuuto Tower and defeat the villain, but it's Crowning Moment of Awesome while it lasts.

Music

The Music Video for Asian Kung Fu Generation's "After Dark" features a man randomly sprouting wings on his back one day, and desperately hiding them until some window-washer is dangerously close to falling off a building. Awesomeness Ensues.

Video Games

Played kind of lopsided in Kingdom Hearts I and II. For both of the ginormous final bosses, you suddenly gain the ability to fly through the air, without wings. It sort of makes sense because in I, there's a level you could already do this. In II, you can get this ability beforehand, but only at an ungodly high level. In the usual player's case, both are the gameplay equivalent of a Giant Space Flea From Nowhere.
- It's actually more of a Chekhov's Skill from Sora and company's time in Neverland in the first game and a function of Sora's costume upgrade in the second. In the first game Sora only starts flying during the final battle after gaining the resolve to fight in a variation of Think Happy Thoughts with Heroic Willpower.
Interactive Fiction example: Photopia. The way to escape The Maze is to 'go up'.. The author mentioned that he got the idea from Ron Hansen's Mariette in Ecstasy.
Lloyd in Tales of Symphonia suddenly sprouts wings to save the world in the ending. Though this was not entirely unexpected, as his Exsphere's special nature had been foreshadowed for much of the game.
In Grandia, the Icarians are a winged race that has entirely died out - except for Leena and her sister Feena. The latter is revealed when she and Justin fall off an airship.
Eddie suddenly gains the ability to sprout awesome-looking demon wings in Brutal Legend. Apparently The Power of Rock has to be invoked, because the wings disappear whenever he's not in a Stage Battle.
In World of Warcraft, Baron Sablemane at first gives the player lots of things to help them kill the gronns. At the end of the chain, in Alliance version, he personally help the player to fight Goc, starting with some...questionable words, and shortly after transformed into his true form, he is a black dragon all along. Once finished, he even apologized to the players for his "startling transformation".

Web Comics

Aldran, the necromancer and party leader in Antiheroes, didn't reveal that he has wings until the party confronted his archenemy and twin brother, who also has them. May be justified by his secretive personality, as he didn't even admit his name was Aldran until the 36th strip.
Marsha in CRFH. After being bitten months ago by vampire potatoes. She found out when she was about to kill herself by jumping off a tall building, but changed her mind, but then the cat with a piece of Dave's soul surprised her and she fell off.
Happens in about half of Aylee's forms in Sluggy Freelance. Apparently her body has decided that it's too useful not to have flight.

Western Animation

The Monarch's henchmen themselves didn't know the wings on their butterfly-themed costumes could be used to fly until someone tried to in the second season finale of The Venture Brothers.
In one of the Wallace and Gromit films, Gromit is heading toward a cliff in a runaway motorcycle sidecar, falls off, and...pushes some buttons that suddenly cause it to sprout wings and a propeller.
Lavana in Brats of the Lost Nebula. Twisted in that it's only the second episode, and the rest of the team knew all along - they just didn't tell the guy that was patrolling with her.
The series-ending "Endgame" of Transformers Animated is a variation on this: Megatron has captured the massive Autobot Omega Supreme, and in order to combat him should Megatron try to use him against the other Autobots, Ratchet and Sari build a jetpack with wing stabilizers for Optimus Prime.