House Harkonnen is a noble house which has a long history reaching up to the dark days of Butlerian Jihad. It's first ruler known is Abulurd Harkonnen, who acted cowardly in the Battle of Corrin. The event led to a bitter rivaly, a kanli between his house and the House Atreides. Since then the two families ran a bloody feud.
Harkonnen are known for their brutal ways. They are ruthless and clever rulers. Under their rule, many of their fiefdoms turned in to profitable planets. They are known to make whale-fur trade from Lankveil and Spice harvesting in Arrakis.
In the series, the house is ruled by gluttony, homosexual Siridar Baron Vladimir Harkonnen. He keeps a twisted mentat, Piter de Vries as his mentat-assassin, and promotes a rivalry between his two nephews and possible heirs. His first heir is Count Lankveil Gloussu Rabban, who goes by the name "the Beast" for the murder of his own father. The other potential heir is Feyd-Rautha, an elegant yet ruthless boy. Feyd-Rautha becomes Baron's favorite candidate with his skills.
At the beginnig of the series the house holds fiefdom of the planet Arrakis, which is in a way center of the universe. Because of it's great commodity, "Spice", the planet has become a center of power-plays across the Universe. Baron Harkonnen plots a sinister plan to destroy House Atreides and to keeps his control on Arrakis. Baron makes an aggreament with Padishah Emperor Shaddam to force him to Atreides to hold the fiefdom of Dune, and to move them out of Caladan, their home-planet. Later on, Baron uses a decoy, Doctor Yueh, to shut down shield generators of Atreides Palace in Arrakis to attack with combined forces of his armies and Imperial Sardaukars. The conflict ends with the death of Duke Atreides and escape of his wife Lady Jessica and Paul. During his death, Duke unleashed a toxic gas and kills Baron's mentat Piter.
Paul Atreides gains a great power over the natives of Arrakis, the Fremen, and launches a series of assaults on Imperial forces and Harkonnen forces on the planet. Baron Harkonnen replaces the governor with Rabban. Rabban, with his extreme ways, gains the hatred of Fremen and strengthens their will to fight. Baron's plans to make Rabban bad with people and to send in Feyd-Rautha to make him look like a savior collapses with increased attacks on Harkonnen outposts. Emperor, enraged by Baron's inability to handle the crisis, sends legions of Sardaukar and attends to the battle personally with his large retunie. This attempt ends in vein when Paul Atreides, know known as Muad'Dib, storms the imperial encampment. His sister Alia, kills the Baron with a poison stinger, and Paul duels with Feyd-Rautha. With Feyd-Rautha's defeat, the House's future is sealed. And House Harkonnen collapses.
House's Relations and importance for Bene Gesserit Plan
The House is related to it's nemesis, Atreides in so many ways. Paul's mother, Lady Jessica is a Bene Gesserit nun, a seed of Baron Harkonnen. Her mother, a Bene Gesserit like her, was raped by the Baron. Bene Gesserit seeks to couple Lady Jessica's possible daughter with Harkonnen heir Feyd-Rautha to achieve their great plan. A messiah, a male Bene Gesserit. Their plans are destroyed with Jessica's decision to give Atreides a son, rather than a girl.
Harkonnen insignia is a crowned Griffon.