Holdout is a Campaign Achievement for Halo 3 on the Xbox 360.
It is earned when one finishes the campaign mission Crow's Nest on the Normal, Heroic, or Legendary difficulties, and gives 20 Gamerpoints to the player.
It is represented by a blue plate with a roman numeral II on it.
Note: The player must finish the level completely through from Mission Start, or the achievement won't be unlocked.