Sopron was an exotic alien life-form native to an unnamed planet visited by the Liberator. Avon described it as the most sophisticated life-form he had ever encountered.

To the human eye sopron appeared as a fairly nondescript rock, but existing on the permanently dark hemisphere of its planet had led it to developing an unusual defence mechanism. It projected a slightly distorted reflection of anything perceiving it through other than direct visual means: to Zen and Orac's detectors it appeared to be a marginally more powerful computer, while Cally's telepathy sensed what she thought was her dead parents, but was actually a more powerful version of herself.

Avon was able to contrive a synthetic analogue of sopron which he fitted to a landing module he found on the planet Kairos. When scanned by the Liberator, the module registered as a powerful spacecraft with slightly greater weaponry and speed.(C: The Harvest of Kairos)