It says in the Manual of Muad'Dib:
"To attempt an understanding of Muad'Dib without understanding his mortal enemies, the Harkonnens, is to attempt seeing Truth without knowing Falsehood. It is the attempt to see the Light without knowing Darkness. It cannot be."
I therefore offer my synopsis of the key figures in House Harkonnen.
House Harkonnen is, in many ways, the antithesis of all that House Atreides stands for. Many of the Atreides servants, most notably Gurney Halleck and Dr. Wellington Yueh, threw in their lots with the Atreides because of their hate for the Harkonnens. Gurney's inkvine scar was given to him by Count Rabban, a relative of House Harkonnen. Dr. Yueh's wife, Wanna, was held by the Harkonnens and used as a tool to subvert his Imperial Conditioning. The governors of Harkonnen territories use "every degradation of the spirit imaginable" (in the words of Duke Leto) in dealing with their populations, and their schemes always smack of treachery.
Siridar-Baron Vladimir
Harkonnen (): It is mentioned in Dune that, while Leto Atreides is an
Imperial Kinsman, the Harkonnen titles came purely from the CHOAM pocketbook.
The Harkonnens' deep hatred for the Atreides stems from the fact that Bashar
Abulurd Harkonnen was banished for treachery by an Atreides after the Battle of
Corrin. The humiliation seems not to have healed with time, as the descendant of
that banished Harkonnen, Baron Vladimir, gloats most magnificently when Duke
Leto is brought, bound before him. When the political winds force House Corrino
to side against the Atreides, the Baron is more than willing to spend his
carefully guarded reserves of spice to pay for the passage of the legions of
Sardaukar to Arrakis, as well as providing them with Harkonnen livery to hide
the Padishah Emperor's part in the attack. Baron Harkonnen is a man of
questionable sexual leanings also, as he seems to favour young boys, including
the na-Baron, Feyd-Rautha. In his youth, it seems, he experimented sexually, and
produced a child by a Bene Gesserit, the Lady Jessica, whose daughter, Alia,
later killed him. This was not the end of the disturbingly stubborn Baron,
however, as he later returned in Children of Dune, to take over the mind of the
one who killed him. Alia's pre-born awareness of her ancestors left her prone to
this attack, with the possession of the Baron, Alia became the Bene Gesserit
Abomination.
Feyd-Rautha Harkonnen
(): Feyd-Rautha was not actually a Harkonnen by direct descent, but took the
name when his uncle, Baron Vladimir, chose him as his heir-designate. He is the
son of Abulurd Rabban, youngest demibrother of the Baron, who renounced the
Harkonnen name when he received the district governorship of Lankiveil.
Feyd-Rautha is a youth of devious cunning, who made an attempt on the life of
the Baron, by secreting a poisoned needle in the leg of a slave-boy, who was to
"divert" the Baron. This plan only failed because Thufir Hawat was at
the time serving the Baron Vladimir. The good Thufir's aid had been previously
given to the na-Baron, however, in an attempt to have the Baron's slavemaster
replaced by arranging it that an undrugged slave be placed in the arena to fight
Feyd-Rautha. Feyd's own man then bevame slavemaster, but was later ordered
killed by the Baron. Feyd-Rautha was killed by Paul Atreides in single combat,
after the Fremen victory over the Imperial forces. Thus the kanly, or vendetta,
between the Atreides and the Harkonnens was settled.
Count Glossu Rabban
(): Count Rabban, or Beast Rabban as the Arrakeen citizens came to refer to him,
was regent-siridar of Arrakis when it was held by the Harkonnens. He is also
Count of Rabban-Lankiveil, where it can be conjectured that he met Gurney
Halleck, while he was a Harkonnen slave, and gave him the scar across his jaw,
not to mention killing his entire family. Halleck joined the service of the
Atreides after that, vowing to be revenged on Rabban. After the death of the
Piter de Vries, the Baron relied once more on Rabban to govern Arrakis. The
Baron described him as "a muscle-minded tank brain" who squeezed the
spice mining industry on Arrakis relentlessly, as the Baron planned for
Feyd-Rautha to take over and be hailed as a benign hero by the people of
Arrakis. Unfortunately both the Baron and Feyd-Rautha died before this plan
could come to fruition. Rabban also died in the confrontation between Fremen and
Imperial forces at the end of Dune.
Piter de Vries (Mentat)
(): Piter, the twisted Mentat, was the force behind many of the Baron'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 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.
--All synopsis on the Harkonnen House were provided by Phil Roberts