Duncan Idaho (10148 AG - 10191 AG) was a swordmaster in the service of House Atreides, and one of Duke Leto's right-hand men, with Gurney Halleck and Thufir Hawat. Duncan Idaho was said to be very handsome. He had black, curly hair, a dark complexion, and green or blue eyes. During the days of the original Duncan Idaho, and during the time of the God Emperor, he was regarded as something of a ladies' man.
Training and Loyalty
Duncan came under the service of the Atreides after observing that they ruled in stark contrast to the Harkonnens. The Atreides appeared to garner fierce loyalty from those who served them, and Duncan was no different. However, as Atreides Swordmaster he maintained a hypervigilance against potential threats to the Atreides, even within their own ranks. As a result, he developed a distrust of the Lady Jessica, as he knew that her Bene Gesserit origins were likely to involve some secret scheme against the Atreides. However, Duncan underestimated Jessica's love for her Duke, which was so strong that she disobeyed her Sisterhood. Indeed, in matters regarding the Lady Jessica, Duncan's judgment was somewhat clouded, since he was secretly in love with her.
A graduate of the Ginaz school, Duncan was charged by Duke Leto with training his son Paul in the art of war. This involved hand-to-hand combat and military strategy. These skills Duncan imparted on the young Paul in conjunction with Thufir Hawat and Gurney Halleck. When compared to Gurney, Duncan appeared to fight with more finesse but Gurney was regarded as more lethal, typically beating Duncan six times out of ten. This seemed to give Paul a well-rounded education. 
Move to Arrakis
Later, when the Atreides gained the Arrakis fief, under the order of the Emperor, Idaho became Duke Leto's ambassador to the Fremen, the people native to Dune that Leto hoped would ally with him in the feud against House Harkonnen. Idaho was so impressed with the Fremen, that he took dual allegiances, one to the Atreides, one to the Fremen.
When the Emperor launched an attack on Arrakeen in the guise of Harkonnen troops, Idaho was killed by the Emperor's Sardaukar by a blow to the head, but not before he dispatched no less than nineteen Sardaukar soldiers single-handedly. In so doing, he rescued the Duke's son Paul Atreides, who later became the first Emperor in the dynasty of House Atreides, and Duke Leto's concubine, the Lady Jessica.
After Paul's ascension to the throne, Idaho was returned to life as a ghola, a clone made by the Bene Tleilax and gifted to Paul Atreides, which was supposed to tempt the Kwisatz Haderach into becoming that which he despised. Known as 'Hayt' in his ghola incarnation, Idaho was trained as a Mentat and a Zensunni philosopher. He had no memory of his former life, but constantly felt vague hints and reminders of his previous incarnation that made him hope he could recover those memories (this had never previously been possible with gholas).
Failing to destroy the Emperor psychically, Hayt was programmed to kill Paul against his will. In the ensuing trauma imposed by his inability to reconcile his programming and his innate love for the Atreides, Hayt recovered his memories as Duncan Idaho, up to and including his death at the hands of Imperial Sardaukar. He stopped the attempt on Paul's life, and became once more a loyal Atreides servant. This became the crux of a Bene Tleilax plot to overthrow Paul by demonstrating that they could create an exact equivalent of his dead wife Chani, but only if he abdicated his throne.
Idaho married Alia, Paul's sister and Imperial regent to Paul's children Leto II and Ghanima. However, Alia became possessed by the memory-ego of her ancestor, Baron Vladimir Harkonnen, who sought to destroy the Atreides empire. Recognizing this, Idaho remained loyal to the Atreides and escaped to the desert to protect the children. In order to get Stilgar to join the Fremen opposition to Alia's rule, Duncan killed Javid, Alia's secret lover, on the neutral ground of Sietch Tabr, then insulted the naib Stilgar so deeply that he was forced to kill Idaho. Duncan's second death, as Duncan knew it would, brought the Fremen into direct opposition to Alia.
Idaho then reappeared as a series of gholas when Leto II ruled as a human-sandworm hybrid for approximately 3,500 years. After the death of every ghola, Leto would have him replaced with a new one. Thus, Leto continually had an Idaho ghola to serve him as Swordmaster at all times, and as leader of the Fish Speakers. To Leto, Idaho represented loyalty, humanity and the spirit of the unknown, something which the God-Emperor, having perfect prescience and memories of all his ancestors, knew nothing of (Leto also implied that Duncan was needed for the Golden Path to come to fruition). The ego-memories of Leto I and Paul within Leto II loved Duncan, which was another reason why the God Emperor enjoyed Duncan's presence.
The Idaho gholas, with their memories restored, fought to deal with what the Atreides had become in Leto II, which Duncan saw as a corruption. Prior to Leto II's rule, the hallmark of Atreides rule was justice. However, Duncan believed that Leto II's reign was one of religious tyranny and oppression. Idaho's old-fashioned conscience would rebel, leading some of the Idaho gholas to attempt to kill Leto (who was invulnerable to all but water and the extreme violence of a sandworm). Leto noted that only nineteen of "his" Duncans had survived long enough to die of what was considered "natural causes". In just about all of these rebellions, the Idaho ghola was killed by the God Emperor himself.
After a brief period of mourning, the God Emperor would order another Idaho ghola from the Tleilaxu. The man usually showed up believing he had gone insane, in shock at how the Universe had changed since his "death" since most Duncans only possessed the memories of the original Idaho. In the latest case however, Idaho remembered his second life as well(this was presumably a test of the Tleilaxu to see if Idaho could remember the lives of the gholas if their DNA would be with him). If the new ghola survived Leto II's first interviews, he would serve the God Emperor until his almost inevitable rebellion.
After the death of Leto II, the Bene Gesserit became the consumers of Idaho gholas. However, the Bene Tleilax kept killing the gholas after only a few years. Not knowing exactly what purpose Idaho would serve, the Bene Gesserit suspected that the Tleilaxu were using the gholas to control the timing of his release upon the universe, implying some Tleilaxu purpose in addition to their own. However, the twelfth ghola survived and the project of having him remember other gholas was complete. Duncan Idaho remembered the lives of about a thousand gholas of himself and was now mentally about 6000 years old. The twelfth ghola was possibly the last as well.
Miles Teg, the Bene Gesserit Bashar was commissioned to restore the memories of Duncan Idaho and managed to do so. However, when Murbella, a captured Honored Matre tried to bond with Duncan, the Tleilaxu plan came into play, and all of the memories of the previous Duncan Idaho gholas were released. Over the next few years, Murbella and Idaho sired four children.
Idaho was later used to tutor and condition a young Miles Teg ghola, but later escaped with his ward and Sheeana, and others, aboard the no-ship Ithaca into unchartered space to escape from the now-combined Gesserit/Matres group, the New Sisterhood. Exhibiting prescience abilities, Idaho was the only person that could see the Tachyon net that the pair of mysterious and powerful elderly-looking entities known as Daniel and Marty had cast out to ensnare the Ithaca. To escape this net, Duncan Idaho deleted all of the navigation records of the no-ship, rendering those onboard truly lost.
The Prelude to Dune trilogy describes Duncan's childhood and exploits on his homeworld Giedi Prime, while according to The Dune Encyclopedia he was a native of Caladan. The Prelude also differs from original Dune novels by having Duncan in mortal fights before the Grumman conflict, while both the original Dune series as well as the Encyclopedia state that Grumman was the first time he had actually killed.
Behind the Scenes
Duncan Idaho was the only character to appear in all six of Frank Herbert's original Dune novels, albeit in different incarnations. He also appears in all of the Expanded Dune novels, with the exception of the Legends of Dune trilogy which occurs deep in humanity's past. Despite only having a relatively minor appearance in the original Dune, the character became the focal point of the overall saga, and his existence as a series of gholas was to serve an ultimate purpose.
In the 1984 Dune movie, Duncan Idaho was portrayed by the late actor Richard Jordan. In the Sci-Fi Channel mini-series he was portrayed by James Watson, while the first Duncan Idaho ghola was portrayed in the Children of Dune miniseries by Edward Atterton. In the 2021 film adaptation, Duncan is set to be portrayed by Aquaman star Jason Momoa.
- Dune - First appearance; original
- Dune Messiah - Ghola
- Children of Dune - Ghola
- God Emperor of Dune - Ghola
- Heretics of Dune - Ghola
- Chapterhouse: Dune - Ghola