Feyd-Rautha Harkonnen is a key character in the science fiction novel Dune by Frank Herbert.

Feyd-Rautha is the younger nephew of Baron Vladimir Harkonnen and figures heavily in the Baron's plans to gain power. The Baron favors the handsome and charismatic Feyd-Rautha over Feyd's older brother Glossu Rabban, "The Beast," because of Feyd's extreme intelligence and his dedication to the Harkonnen culture of sadism and cruelty.

The Baron planned a strategic marital alliance, hoping to marry Feyd to one of the daughters of the Emperor Shaddam IV, and giving the Harkonnens influence or control over the throne. To promote Feyd's power, he is to be installed as ruler of Arrakis after a period of tyrannical misrule by Glossu Rabban, making Feyd appear to be the savior of the people.

Feyd, like Paul Atreides, is also the product of a centuries-long breeding program organized by the Bene Gesserit, who planned their own marital alliance, joining a Harkonnen son to an Atreides daughter, uniting the powerful houses, ending their feud, and assuring their offspring would have a high probability of becoming the Kwisatz Haderach. For this reason, Jessica Atreides' decision to defy the sisterhood and to produce an Atreides son, Paul, establishes an irreconcilable tension between Feyd and Paul as the scions of their bitterly opposed noble houses. The risk of one or both of these young men being killed, destroying thousands of years of genetic engineering, is so great that the Bene Gesserit send an envoy to seduce Feyd and conceive a child, salvaging his genetic material. During this seduction, the Bene Gesserit may have used a form of hypnotic suggestion to make Feyd vulnerable to a command which will cause complete muscle paralysis, a technique they sometimes use on individuals who are considered highly dangerous.

Feyd's ambition and impatience to inherit the Baron's title and power allows him to be manipulated by Thufir Hawat, a counselor to the Atreides who is captured by the Baron. Both the Baron and Feyd are nearly assassinated as a result of Hawat's machinations.

Feyd is famed for his prowess in single combat, and his willingness to break the formal rules of "kanly" that in the universe of Dune govern this type of challenge, by using poison on his weaponry. He nearly succeeds in killing Paul Maud'dib in ritualized single combat, while Paul is deciding whether to try the paralysis command and owe the Bene Gesserit his victory or whether to risk his life against Feyd in a "fair" fight. Despite his treachery, Feyd is himself killed.