Idaho was portrayed by Richard Jordan in David Lynch's 1984 film version of Dune, and by James Watson in the 2000 Sci-Fi Channel miniseries.

Paul Atreides notes Duncan's "dark round face" and "feline movements, the swiftness of reflex that made him such a difficult weapons teacher to emulate."

Duncan is fiercely loyal to House Atreides, a skilled pilot, and as a Swordmaster of the Ginaz is a gifted hand-to-hand fighter.

[5] In the fight that ends with his death in Dune, Duncan kills an unheard-of 19 Sardaukar, the Padishah Emperor's fearsome supersoldiers.

In 1976's Children of Dune, Lady Jessica tells Duncan that he was drawn to her daughter Alia because "you wanted a girl you saw as a younger version of me.

"[7] In God Emperor of Dune (1981), the latest Duncan ghola discovers that one of his predecessors had fathered a child with a woman named Irti who closely resembles Jessica.

[8] At the time of Frank Herbert's original novel Dune (1965), Idaho is a Swordmaster of the Ginaz in the service of House Atreides and one of Duke Leto's right-hand men (with Gurney Halleck and Thufir Hawat).

When the Emperor's dreaded Sardaukar attack Arrakis in the guise of Harkonnen troops, Idaho initially survives the assault and saves Leto's son Paul Atreides and concubine Lady Jessica.

[6] Idaho returns in Dune Messiah (1969) as a ghola named Hayt, made by the Tleilaxu and given to Paul Atreides, now Emperor.

As the ghola is of Tleilaxu design, Bijaz employs a specific humming intonation that renders Hayt open to implanted commands.

But this is only part of the true plan; the emotional distress of the attempt allows Hayt to recover the buried memories of Duncan Idaho, up to and including his death at the hands of the Imperial Sardaukar.

It is also implied that Duncan is needed for Leto's plan for humanity's ultimate survival — called the Golden Path — to come to fruition.

The current Duncan is intended to mate with Siona Atreides, the end product of Leto's breeding program: she is invisible to prescient sight.

[8] Fifteen hundred years later in Chapterhouse: Dune (1985), the Bene Gesserit Bellonda assesses the many Duncans who came before: In the original and early gholas, his character had been dominated by impulsiveness.

When Murbella tries to bond Duncan, the Tleilaxu's plan comes to fruition, and he becomes aware of the memories of all the other Idaho gholas, though he is also imprinted to her.

Duncan restores the memories of the Miles Teg ghola, and escapes in the no-ship, evading the trap set for him by the strange couple.

They don't learn until near the end that the Enemy is the revived empire of thinking machines, and the old couple are actually the computer-entity Omnius and the robot Erasmus.

Overwhelmed by the unexpected revelations, Duncan decides to unite humanity and the thinking machines—after Cenva permanently removes Omnius from existence—rather than bring about the absolute destruction of intelligent technology for the second time in history.

According to the Prelude to Dune prequel trilogy (1999–2001) by Brian Herbert and Kevin J. Anderson, Duncan Idaho is born on the planet Giedi Prime, under the Harkonnen Regime.

In the trilogy's second installment Dune: House Harkonnen, Duncan undergoes the immense rigors needed to be a Swordmaster; he is promoted to the title, alongside a Grumman friend named Hiih Resser, and helps defeat a mob of insurgent students.

At the time of Dune: House Corrino, Duncan is an instrumental part of the liberation of the planet Ix from the Sardaukar and Tleilaxu, and even manages to defeat Count Hasimir Fenring in single combat.

[15] In the 2003 miniseries sequel Frank Herbert's Children of Dune, the ghola of Duncan (known in the novels as "Hayt") is played by Edward Atterton.

[17] Emmet Asher-Perrin of Tor.com writes that Atterton "plays the mentat ghola reincarnation of Idaho with all the upright stoicism and vulnerability that the character is owed.