Telos

The planet Telos was at one time the home of the Cryons. It was later colonised by the Cybermen and was the location of the Cyber-tombs. It was the resting place of the last of the Cybermen.

Characteristics
Following Cyberman occupation, Telos was a grey, barren, rocky world. Diamonds, vastial and other minerals could be found on the planet. (DW: Attack of the Cybermen)

History
At one time Cryons, who died instantly when exposed to temperatures above zero degrees, lived on Telos. The Cryons moved under the surface when it became too warm, constructing underground cities refrigerated to the sub-zero temperatures the Cryons needed to survive. The Cybermen later came to steal the refrigerated cities to use as repositories of Cybermen cryonically frozen in suspended animation. The Cybermen killed most of the Cryons. (DW: Attack of the Cybermen)

The Cybermen from Lonsis were twice destroyed by the Eighth Doctor. It seems after Mondas was destroyed, the Cybermen moved to Lonsis, planning to invade Earth. They were foiled by Charley Pollard, who infected their ship with temporal corrosion, and later the Doctor, who increased the range of a Quantum Crystalliser programmed to destroy them. The few survivors of these attacks colonised Telos, while Cybermen from other parts of the Universe colonised other planets. (BFA: Human Resources)

Five hundred years after the last known encounter between humanity and the Cybermen, an archaeological expedition from Earth, led by archaeologist Parry (but financed and masterminded by Kaftan and Eric Klieg of the Brotherhood of Logicians) landed on the planet to find the Cybermen and to revive them. With the Cybermen as their army, the Brotherhood planned to impose a regime of pure logic on human society. The Cybermen and their leader, the Cyber-Controller, were resurrected. The Second Doctor was able to seal them back inside their "tombs" and to electrify the outside gates. (DW: The Tomb of the Cybermen)

The Cyber-Controller was not killed, as the Doctor had believed, but survived, and had installed a base, known as Cyber-Control underground, supervising operations in 1985 London, with which they had a communications link, and fighting the Cryon rebels who remained. The Cybermen at this time employed work parties of humans whose conversions were unsuccessful as slaves to mine the surface of the planet. The Cybermen intended to destroy Telos and to observe its blast pattern for future research. The base was, however, invaded and destroyed by the Doctor (now in his sixth incarnation) with the assistance of the captured Cryon leader Flast. (DW: Attack of the Cybermen)

After the Hotel Historia on Earth was invaded by Graxnix, manager Majenta Pryce decided to flee and relocate to somewhere like Telos, claiming that it could use a little remodelling. (DWM: Hotel Historia)

The Eleventh Doctor visited Telos while trying to save Billy Jones, who had been scattered through time. At this point in time, the cyber-tombs were occupied by Cybus Cybermen who began to wake from the tombs. (VG: The Mazes of Time)

At some point, the planet was shattered by an asteroid impact. (BFA: Telos)