Ice

Ice was frozen water. It was made and used by humans to "cool the drinks". (PROSE: Deadfall)

On prehistoric Earth, an Ice Warrior spacecraft crashed and was buried in ice. (TV: The Ice Warriors) Around 3000 BC, Skaldak was frozen in ice at Earth's North Pole. (TV: Cold War)

The Cold was able to manipulate ice and use it as a weapon, and may have existed within ice itself. (PROSE: Time and Relative)

Some planets had caves made of ice. These included Marinus (TV: The Keys of Marinus) and Shabadabadon. (AUDIO: Terror Firma) On Arthur's World, Morgaine trapped the Doctor in an ice cave. (TV: Battlefield)

Other planets seemed to be completely covered in ice. These included Calufrax, (TV: The Pirate Planet) Ixon, (COMIC: The Therovian Quest) Bruhl, (PROSE: Justice of the Glacians) Serac, (COMIC: The Betrothal of Sontar) a human colony visited by the Fifth Doctor and his companions (PROSE: Cold Fusion) and an ice planet where the Monk was once stranded. (TV: The Daleks' Master Plan)

The core of the planet Spiridon was made of ice. (TV: Planet of the Daleks)