The festival of the Empty Man was one in which occurred on the planet Caladan druing the autumnal equinox of the world.
Story of the Empty Man[]
The local leader of the populace would re-tell the story of the Empty Man -- a man who even though he had devoured so many souls of the innocent, still found himself growing more and more empty. The man, after he became a ravenous killer, became akin to a hollow shell, in an almost ghost-like appearance. Originally the Empty Man was satifisfied with killing every once in a while, just a few times a year -- a wayward sailor or a visiting traveller.
But after a while, the Empty Man became a hated being, a serial killer, roaming the coasts of the Western Continent north and south of Cala City; looking for the innocent to kill. Eentually, the good townspeople of the area grew tired of their loved ones disappearing, and they banded together, hunted down, and killed the Empty Man. Once they killed him, they found that he was just that -- Empty -- and the husk of his body and being-ness blew away in the wind.
Duchess Jessica and the Empty Man[]
In 10200 AG, after Jessica had returned from a meeting on Wallach IX, with the leadership of the Bene Gesserit order, and had received an offer from them to kill Emperor Paul Atreides Muad'Dib, her son. Jessica compared the state of the Empty Man, with that of her son Paul, who had sterilized so many worlds, but never seemed to be satiated with the lives that were lost. It was after telling the story of the Empty Man to the local townspeople of Cala City that Jessica decided to kill Paul when she came across him again.