A radio series that was created after the model of The Shadow was The Whistler. Running over radio for about ten years, there were at least six Whistler characters though Bill Forman (right) was the longest running Whistler.

The Whistler was the voice of conscience and fate. A dark dis-embodied character who while he had no physical presence in the radio plays, he was very much a part of the episodes.

Also, another series run with a conscience - episode three of the "Clan of the Fiery Cross" from the Adventures of Superman.