Venatori are an evil organisation in Dragon Age. Their are Tevinter nationalist group that wishes Tevinter returns to its glory when whole continent of Thedas was under their rule. When Corypheus found them and introdcused himself as a magister of old they began to serve him. As they worship him as a god they eventually became a sect and under his command they gathered resources to conquer the world for him.
Calpernia is their leader who buys and captures slaves to recruit them.
Gereon Alexius try to recruit rebel mages to their ranks but the Inquisitor can prevent it.
Livius Erimond brainwashed grey wardens and tries to use them to bring Nightmare Demon to Thedas.