A plague, also known as an epidemic or a pandemic, was a widespread outbreak of an infectious disease. (TV: The Visitation) Less commonly, a plague could refer to an infestation of pests such as spiders. (TV: Arachnids in the UK)
In 1592, Robert Greene died from a plague. (COMIC: A Groatsworth of Wit)
In 1628, a plague ravaged London. (PROSE: The Roundheads)
Another plague began in 1664. The first victims were native to the parish of St. Giles-in-the-Field. (PROSE: The Book of the War)
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)
After the Eternal War ended, Gallifrey was ravaged by a plague which only a few survived. It killed everyone who knew that it was Rassilon's mistake which had brought the Yssgaroth into the universe. (PROSE: The Pit)
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)
In Ecto-Space, six-sevenths of the population of Jokastarna were wiped out by a "plague" in the Year of the Flame. Over two hundred years later, Emperor Lukor lived in fear of a new outbreak of the plague, and had vast, inhumane experiments carried out on the caveys of the Inner Kingdom, inoculating them with new, man-made strains of the plague, in order to develop antidotes and artificial immunities ahead of time. These experiments were brought to an end when they were discovered by the Mistress and K9, with them managing to create a permanent cure, capable of altering itself to match any new strains, using cypherdurite. (AUDIO: The Choice)