Guardian Sentinel

The Guardian was a Forerunner Sentinel located at the Ark. They bear a strong resemblance to the S'pht Compilers from Marathon, a previous Bungie game and also the Forerunner hologram in the multiplayer level Epitaph

The Guardian Sentinel was originally set to appear as a fighting enemy in a campaign level that later became a multiplayer level Guardian but was removed, and featured in The Art of Halo 3 instead. It was stated that the player would have been able to rip out the Guardian's eye beam and use it as a weapon in the campaign level.