The Sentinels are the protectors of the known universe, defending worlds from invasion and policing intergalactic criminal activity. It was founded long ago by some denizens of Earth who discovered exotic matter infused crystals, making them some of the first Powered in human history. Having come from Earth, the Sentinels do protect it, though they do not protect any planets that have not discovered and utilise Bridge Drive technology.
The Sentinels
Intergalactic Protectors