Spontaneous human combustion

Spontaneous human combustion referred to cases where humans ignited without apparent reason. According to Mike Yates, it was ten times more likely to happen to UNIT soldiers than civilians. (PROSE: No Future)

At some point during the 1890s, a spate of at least nine human combustions were reported in Victorian London. This case was pursued by the newly regenerated Twelfth Doctor and the Paternoster Gang after witnessing a tyrannosaurus rex the TARDIS had brought to London spontaneously combust. It was revealed to be the work of the Half-Face Man and his Clockwork Droids, who had their victims incinerated to mask the organ harvesting they performed. (TV: Deep Breath)

Chris Cwej and Iris Wildthyme, on a mission for their superiors, investigated a case of spontaneous human combustion in Plymouth, 2020. This was the cause of an alien researcher, who Iris speculated did not understand human biology, and was from another plane of existence altogether. (PROSE: Flickering Flame)