Growing Wings

Not every Winged Humanoid is born that way. Sometimes, they have to go through Metamorphosis first. This can occur in any number of ways:
 * The character wakes up one morning to discover tiny wings on their back, which grow over time until they are functional.
 * The more realistic the story is, the more slow and painful the change will be. If the keeled sternum and large flight muscles also develop, it can be a mild case of Body Horror.
 * The wings appear suddenly, often as a result of a magical spell.
 * The initial sprouts can be ridges, feathery tufts, or tiny, articulated wings.

Note that this trope is for permanent or semi-permanent wings. Wings that appear and disappear go into the category of Power Gives You Wings.

Anime and Manga

 * Princess Ai sprouts a pair, on account of her unconventional heritage.

Music Video

 * 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 a window-washer is dangerously close to falling off a building. Awesomeness Ensues.