He's Unstoppable!
From Halopedia, the Halo wiki
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 from an Unggoy in Halo: Combat Evolved when the player, as John-117, kills most of the said Unggoy's allies.
Sources
