The Source was a benign deity worshipped by many in the Drenai world, including the Source priesthood. As the name suggests, the deity was considered to be the source of all things, and was believed to directly influence events in the world through inspiration, guidance and the subtle workings of fate.
The evil counterpart of the Source was the demonic Chaos Spirit, worshipped by the Dark Brotherhood.
In the Rigante world, the Source was worshipped by the inquisitorial order of Crimson Priests.