The Chosen One

THERE CAN ONLY BE ONE.

The one who's different from everybody else in a good way. They've got a mark on their body, a power that no one else does, or some other trait that makes them different. It's obvious that they'll be important to the Story, let it be that they're the Hero or the Villain.

Variants of The Chosen One
It's not always a single person who has a special trait; it could be a few people who have it. They're The Chosen Few. Or it could be just two people each with their own trait that is the reverse version of the other, like one can control fire and the other can control ice. That's The Chosen Two. Also, this unique quality isn't always good. Maybe it's something people find repulsive or wrong, like this person is possessed by a demon. In this case, that will be The Chosen Negative One.