achiever

noun

1. One who achieves something.
2. One who tends to succeed; a winner.

   “River hadn't laid eyes on Hobden before, but this had to be him: average height, thinning brownish hair, look of terror as he turned to face this new intrusion even while crushed in an arm-lock by the previous invader, the achiever—except this wasn't an achiever: he was blackclad, wore a balaclava, had a utility belt round his waist, but the ensemble lacked the hi-tech tailoring of the genuine article.”

   “Studies of student behavior and attitudes show that a majority of students violate standards of academic integrity to some degree, and that high achievers are just as likely to do it as others.”