Cannibalism

Cannibalism was the act of eating members of one's own species. While this was sometimes a choice or a lifestyle, for some species this was a natural activity. Mayflies practised sibling cannibalism, leaving only the strongest of them left in the end. (TV: Reset) The term could also be applied to the act of forcibly using parts of a being's physical form to create something else; the Tenth Doctor stated that had "cannibalised" his TARDIS to create his paradox machine. (TV: The Sound of Drums)

Cannibalism was a cultural practice of the Valethske, ordinarily as a form of execution, but occasionally occurred during feeding frenzies. (PROSE: Superior Beings)

The Brynblaidd cannibals killed and ate wanderers near their village every ten years, until 2007. (TV: Countrycide)

At some point in Tennessee, there was a case of cannibalism, though the culprit claimed not to remember the crimes. (PROSE: The Juror's Story)

Alan Jackson at first thought the Slitheen were cannibals when he saw their skin suits lying around. (TV: The Lost Boy)

Esposure to the Rift caused Paul Talbot's DNA to mutate and his metabolism to run wild. He became ravenously hungry, and was unable to stop himself eating his flatmate, a pedestrian, and attempting to eat Jack Harkness. (PROSE: Monster)

Mother Nothing was a cannibal who resorted to consuming her entire race, including her hatchlings, when her home planet was struck by a great famine. (AUDIO: One Enchanted Evening)

According to the Second Doctor's recollection, humans in the Far Indies ate their own kind. He and Shockeye also wrongly (PROSE: The Drosten’s Curse, TV: The Gift) believed that shepherd's pie was made from a shepherd. (TV: The Two Doctors)

The Rezzies of Paradise Towers practiced cannibalism. (TV: Paradise Towers)