Piter De Vries
Piter, the twisted Mentat, was the force behind many of the Baron Vladimir Harkonnen's schemes, as a Mentat, he was capable of constructing many a treacherous plot with devious subtlety. Unfortunately, he was killed by Duke Leto before he could bring his overwhelming cruelty to bear on the planet of Arrakis, thus throwing a spanner in the works of the Baron's plan. It was the unforeseen death of Piter de Vries that forced the Baron to place Glossu Rabban in control of Arrakis. Piter seems to have been fond of seeing people suffer, he was, it is intimated, adept at the art of torture, and a formidable killer.