One of the main species in the Blame! universe.
Their behavior is akin to that of white blood cells, protecting access to the Netsphere and hunting down anyone barred from entry. However, because of interference by the silicon creatures, every human being in the Solar System has been barred from entry to the Netsphere and the Safeguard consider all humans to be targets.
Safeguards with higher rank have more "free will" and human appearance, but those who are not disguised as humans usually have a -|- mark on their heads.