King Edward II of England (1284 – 1327) is believed to have been killed by the insertion of a red-hot iron rod in his rectum.
The story was reported by Sir Thomas de la Moore :
« On the night of 11 October while lying on a bed [the king] was suddenly seized and, while a great mattress… weighed him down and suffocated him, a plumber's iron, heated intensely hot, was introduced through a tube into his anus so that it burned the inner portions beyond the intestines ».
The king supposedly deserved this tragic end in order to punish him for his bisexuality.
This theory became popular thanks to The Brut chronicle and was later adopted by Maurice Druon in The Accursed Kings. Yet, other sources pretend that the king had simply been suffocated or strangled, or even that he had died from natural causes.
That's really not cool! O.o