He’s Unstoppable!
He’s Unstoppable! is an achievement in Halo: Combat Evolved Anniversary. It is awarded for completing any level on either Heroic or Legendary difficulty without taking any damage to the player's health.[1]
It is represented by the Legendary difficulty icon with a symbol of a white cross inside a red hexagon on the Sangheili skull.
Trivia
The name of this achievement is a direct quote made by Unggoy NPCs in Halo: Combat Evolved, when most of said Unggoy's allies are killed.
Sources