The Invincible medal resembles a blue and cyan bulls-eye target sitting on top of a ten pointed blue star; it is awarded to individuals after killing 30 opponents in a row without dying on multiplayer matchmaking, or after killing 100 opponents in a row without dying on firefight or campaign.
- It has been proven that the highest spree possible is 255 kills. Even if you get more kills after that number, without dying, it will still say that your highest spree was 255 kills. This is most likely because 255 is the maximum value representable by an eight-digit binary number, and therefore the maximum representable by an unsigned 8-bit byte.
- Earning this medal in campaign or Firefight in Halo: Reach will unlock Jun-A266's helmet for the player's Xbox 360 avatar.