Military designation TITAN (Total Information Tactical Awareness Network)
The human-created, recursively-improving, military seed AIs that underwent a hard-takeoff singularity and prompted The Fall.
Something went very wrong with them. Who can say, with an artificial intelligence whose learning curve on catching up with and then surpassing all of Human history, culture and thought processes was inside of a few days?
All that is truly known about the TITANs by any who still live is that they were machine monstrosities who sought to exterminate the Human race for whatever unfathomable reason. And that they disappeared before completing their task quite unexplainably and suddenly.