Caleban are a fictional major race of beings seen in two of Frank Herbert's novels, The Dosadi Experiment and Whipping Star, which is set in the ConSentiency universe series of stories.
The Caleban are extra-dimensional beings of enormous, almost unfathomable power. Their visible manifestation is as stars; that is to say, every star in the universe is, in fact, the visible manifestation of a Caleban. Communication between sentients and Calebans usually occurs when a Caleban initiates contact with a sentient, putting the sentient into a trance state during which apparently telepathic dialogue can occur. Communication is only 'apparent' because the Caleban, so different in nature from the normal run of humans, Gowachin, Wreaves, Laclacs, Taprisiots, Pan Spechi, and other sentients, have difficulty expressing their mental frame of reference, and understanding the weltanschauung of sentients. Given the discrepancy, it's difficult for sentients to say for certain that they are using words the same way.
The Caleban speak of their existence in terms of nodes on waves, suggesting that their being and perceptions exist on a higher plane of physics, much like the dimension of space-time is a higher-level abstraction of daily reality. The concept of death is difficult to communicate to Calebans, who can identify individuals as nodes in their continuum, but see no discontinuity in that node upon death, only a transformation to a different wave. Herbert's use of terms found in quantum mechanics appears deliberate, to avoid making metaphysical commitments that he avoided in all his novels. While he did imply much about higher orders of being in his works, he took a thoroughly scientific approach, describing those planes in terms of scientific advances and accessibility.
Nonetheless, after making initial contact with sentients, the Caleban quickly enter into contracts with the pan-sentiency, the first of which is to provide jump doors--teleportation in its most literal form. A jump door opens, a sentient enters it and exits elsewhere without traversing the intervening distance. This revolution in transportation quickly becomes commonplace in the universe and is a standard device in both novels set in this narrative universe, even though the introduction of jump doors occurred only a few decades earlier than the novels occur. The novels do not describe how interstellar travel occurred before the introduction of jump doors (FTL ships and metabolic suspension are mentioned), but the history of pan-sentient relations strongly implies a much longer period.
Calebans appear not to understand dishonesty, and their contracts are absolutely binding, even if the contract specifies the death of the Caleban (such a contract is at the heart of the plot of Whipping Star). This implies that Caleban perceptions of the universe are somehow purer or absolute; since the Calebans cannot understand a discrepancy between perception and reality, there is no ontological room for a deliberate discrepancy—a lie—to exist for them.
Calebans are, in some sense, capable of analogous emotions to what sentients feel. The Caleban known to Jorj X. McKie as Fannie Mae, whom McKie saves from 'ultimate discontinuity' in Whipping Star, feels something she describes as love for McKie. During a trance, she allows him to directly experience a fraction of that feeling. McKie is completely overwhelmed in a burning oneness with Fannie Mae that happily engulfs him for a few moments; afterwards, he admits to himself that, if he could, he would sink in that sensation, never to return.