Chen-7
From Tardis Wiki, the free Doctor Who reference
Chen-7, also known as the One Day Plague, could kill in a day. Only species with a binary vascular system, such asApalapucians and Gallifreyans, were vulnerable to it. In the case of Time Lords, regeneration would be impossible.
When a Chen-7 plague threatened Apalapucia, the Apalapucians created the Two Streams Facility, which used temporal technology to isolate the patients and stretch out the day into a lifetime. (DW: The Girl Who Waited)
