Wrath

The Wrath were a race that originated from the Shadow Heart that was led by an Emperor which was a computer. (AUDIO: The Acheron Pulse), AUDIO: The Shadow Heart)

They were created and used the weapon known as Acheron Pulse.

As his first attempt to stop them, the Doctor attempted to program them to become a force for good by using his own moral code as a template for their future behaviour. However, by the time he returned to this region of space fifty years later, they had taken this new morality to the extreme and were attacking everyone for any perceived sin.