Sentient planets were planets that were alive. While any planet that supported life could be described as "living," sentient planets were either "connected" to their inhabitants or possessed actual intelligence.
Sentient planets were inherently female in their personality. Some were able to evolve entirely new species, (AUDIO: Earth Aid) while others would be greatly affected by the actions of their native species. The Cheetah Planet was able to metamorphose living matter into Cheetah People due to a high level of artron energy in it's magnetosphere. (TV: Survival, PROSE: First Frontier)
Sentient planets included:
- Albert (PROSE: Grimm Reality)
- Symbios (AUDIO: The Crimes of Thomas Brewster)
- The Cheetah World (TV: Survival)
- Safenesthome (AUDIO: Earth Aid)
- The Valnaxi homeworld (PROSE: The Art of Destruction)
- The flesh planet Mimosa 3 (COMIC: Black Death White Life)
- Akhaten, a parasite described as both a planet and star (TV: The Rings of Akhaten)
The Third Doctor once made reference to the Earth "screaming" as the Inferno Project ripped it apart in a parallel space-time continuum. (TV: Inferno) He also encountered the Star Beast, another living planet, but one that was a predator rather than possessing intelligence. (COMIC: The Hungry Planet)
Although not inherently a sentient planet, Polymos was completely saturated by the Nestene Consciousness, absorbing the life essence of everything that lived there until the planet became the Consciousness. (PROSE: Synthespians™)