A modern order of magicians, in the vein of the Golden Dawn. The IOT are the principal practioners of Chaos Magic.

Here is the first public notice of the IOT from "The New Equinox Magazine", 1978:
Spiritual heirs to the Zos Kia Cultus, the Illuminates of Thanateros are drinkers of the dual ecstacies of the sex and death gnoses. The IOT represents a fusion of Thelemic Magick, Tantra, The Sorceries of Zos and Tao. The non-mysteries of symbolic systems have been discarded in favour of mastery of technique. ...