The Taheen are a race of humanoid creatures but with the heads of animals, most commonly mammals or birds, and often tails or claws as well; they bear more than a passing resemblance to ancient gods such as Anubis or Horus (Egyptian gods). They are thought of as the only truly supernatural beings remaining in All-World, and they themselves consider humans to be lesser beings. Despite this, they are not exactly an elevated race, being as prone to baser vices such as television, pornography and crude jokes as humans are. This causes Tammy the housemaid at Algul Siento to observe that all men are much the same, whatever species they are.
Taheen only appear briefly or are alluded to until the final volume, where they are shown working alongside humans and Can-toi (a hybrid race of the two) at Algul Siento, a prison for psychics. The prison administration favors them as guards due to their keen eyesight; also, the Head of Security, Finli O'Tego, is a taheen with the head of a weasel. Outside the Crimson King's own lands, however, taheen's height and animal appearance makes them next to useless for subversion in a human society. Even Calla Bryn Sturgis citizen Ben Slightman the Elder, who has actually spoken with Finli O'Tego over the radio, is unsure of what a taheen is.
It is hinted that taheen have a culture of their own (a name-change ritual, notably) and that their religious beliefs are quite different (praying often confuses Finli O'Tego). It is also likely that they have a different brain structure to humans, as the telepathic prisoners at Algul Siento are unable to "read" their thoughts, or indeed pick up anything other than a sensation similar to radio static.