Campaign Complete: Legendary is a Halo 3 Campaign Achievement. It is obtained when the player completes the Halo 3 Campaign on Legendary difficulty. This Achievement gives 125 Gamerpoints to the player and unlocks the Campaign Complete: Normal and Campaign Complete: Heroic achievements if not yet earned.
The achievement is still awarded when playing Co-op online and offline. If a player completes every mission on the Legendary difficulty, it will be awarded regardless of who else is playing.
This Achievement unlocks the full EOD Spartan Variant, with the shoulders and chest plate are unlocked by completing The Ark and Tsavo Highway on Legendary, as opposed to the entire campaign. If the player have not yet completed the Campaign on Normal or Heroic, the EVA Spartan Variant and the Sangheili Flight Harness will also be unlocked, respectively.
This achievement takes a considerable measure of perseverance and skill. Helpful tips for accomplishing it are given out by means of the valuable walkthroughs located on each mission article and those on the Campaign chapter of the Piggyback Interactive Halo 3 Official Game Guide.