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) Isen VI prior to being terraformed, (COMIC: Terrorformer) a human colony visited by the Fifth Doctor and his companions (PROSE: Cold Fusion) and a 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)
River Song described herself in the book Melody Malone: Private Detective in Old New York Town as having "ice in her heart". (TV: The Angels Take Manhattan)