Bubonic plague

The Black Death was an outbreak of bubonic plague in which, over the course of centuries, many Europeans succumbed.

14th century
Durac, also known as Death, appeared during a Black Death outbreak in Cardiff until one brave girl fought him to a standstill. (TW: Dead Man Walking)

16th century
William Shakespeare's son Hamnet was a victim. It was grief over his death that saw Shakespeare at his lowest ebb. (DW: The Shakespeare Code)

17th century
In 1666, escaped Terileptil convicts created a deliberately more virulent variant on the black death in order to infect rats with it so as to spread it to Humans. (DW: The Visitation)

21st century
When the Cardiff rift was opened, people with the black death fell through time. (TW: End of Days)