Native to the planet Telos, the Cryons were renowned for their refrigerated cities, which they built to protect themselves from the warmth. The Cryons are unable to survive in temperatures above zero degrees Celsius; at higher temperatures, they boil to death, with steam pouring off their bodies. When the Cybermen invaded Telos, they thought they had wiped out all the Cryons, but some survived in the refrigerated areas of the Cybertombs.
The Cryons have iridescent skin, and their heads seem to be covered in a helmet of ice, with a frost moustache and a ruff of ice around the neck. They have long fingernails, and wear satiny white jumpsuits with diaphanous capes. Some of the Cryons have apparently become ill, causing them to turn a deep purplish color, and it is implied that they emit a rotting scent when this happens.
The Cryons use communicators clipped to their belts, and they have surveillance equipment in their hideaways. They have armed themselves with Cyberguns, which they use to attack the Cybermen when necessary. If attacked with Cyberguns themselves, they practically evaporate.
The Cryons desperately want to destroy the Cybermen and get them off Telos, so when they pick up a distress signal being sent from Earth by Lytton, they contact him and inform them that the Cybermen have invaded their planet. Lytton agrees to help them. However, in the end, Lytton fails at his plan, and the Cybermen are only destroyed when one of the Cryons, Flast, heats up a tin of vastial and destroys the Cyberbase in the resultant explosion. The remaining Cryons are determined that their race will survive.
