We are told:

“They can move in and out of any software still hardwired to their system. That means that anyone that we haven’t unplugged is potentially an Agent. Inside the Matrix, they are everyone and they are no one.”

 

Morpheus – The Matrix

They appear in old ladies wielding carving knives, tramps and truck drivers. They all have innocuous, common names that give them an ambiguous identity… as if their identity (or who they are) isn’t important.

As such, the agents are not representative of any physical entity. They are more like an idea.

As an archetype, they represent the law. The upholding of law is not just limited to police, anyone with a strong sense of righteousness will welcome the opportunity to become a hero for a day. The law is undefeatable, everywhere, but nowhere and protects the system at all costs.