Sentries are Atlantean security droids, they are the airborne versions of the Fixers and have the same role, to protect Atlantis from strange beings, and because of this they will see the recently arrived Michael Ford as a threat. These enemies are only encountered in the 3rd and 5th missions of the game's story mode.
These creatures are even more fragile than the Fixers, a single shot from a weapon is often enough to destroy them. They only feature a single long ranged attack which is not very powerful, so they will always come in large numbers to compensate this. Also they will always stay aloft and within a considerable distance from the player, making impossible to melee them.
- They seem to be armed with Warp Pistols, however they don't yield anything after being destroyed.
- In Invasion Mode due to a recent update to fix crashes, Sentries often spawn below floors with their head sticking out. Getting near one of them can make it go into a wall, and unless a fully upgraded Phase Rifle is used, that game cannot be finnished.