Plague

A plague, also known as an epidemic or a pandemic, was a widespread outbreak of an infectious disease.

In 1592, Robert Greene died from a plague. (COMIC: A Groatsworth of Wit)

In 1628, a plague ravaged London. (PROSE: The Roundheads)

In 1666, a plague was artificially implanted in England by a trio of rogue Terileptils, who implanted genetically modified bacteria into black rats and used their fleas to spread the contagion. However, the Fifth Doctor inadvertently (and presumably fatally) immolated the Terileptils in the Great Fire of London, which he then used to destroy the remaining vials containing the plague. (TV: The Visitation)

In the 1970s, the Silurians under Wenley Moor tried to create an epidemic with their Silurian virus that would wipe out humanity, but the Third Doctor discovered a cure. (TV: Doctor Who and the Silurians)

In the early 21st century, diseases became more numerous and more virulent due to high pollution levels. These new diseases were known collectively as "the plague". Ruby Duvall's mother died from one of the plague diseases. (PROSE: Iceberg)

In 2157, the Daleks used meteorites to spread a plague on Earth prior to their invasion six months later. Whole continents of people died, including Asia, Africa, and South America. (TV: The Dalek Invasion of Earth) The Cybermen infected the crew of Nerva Beacon with a plague. (TV: Revenge of the Cybermen)

The First Doctor's companion Dodo Chaplet accidentally caused a common cold epidemic on the Ark. (TV: The Ark)

The inhabitants of the planet which Hr'oln visited were made extinct by a plague. (PROSE: The Last Dodo)

Apalapucia became infected by a Chen-7 plague. (TV: The Girl Who Waited)

Draconia was almost overwhelmed by a great plague from space, but was saved by the Second Doctor. (TV: Frontier in Space)

On Harmony, a plague wiped out all animal life inside ten years. (PROSE: Planet of Bones)

Inter Minor isolated itself after the Great Space Plague. (TV: Carnival of Monsters)

Nine-tenths of the population of Tara were wiped out by a great plague. (TV: The Androids of Tara)

The Zantraans were forced to leave their home planet Zantrah when it was ravaged by a plague. (COMIC: The Zantraan Invasion)

In the 13th century the immortal human Ashildr lost her three children Essie, Johann, and Rue to the bubonic plague. She recorded these events in her journals as a reminder to herself to never have any more children. (TV: The Woman Who Lived, PROSE: The Triple Knife)