Even by medieval standards, the death of King Edward II of England in Berkeley Castle in 1327 was particularly gruesome. How did he die?
Answer: He was forced to abdicate in favor of his underage son, then tortured, starved and thrown into a pit of rotting corpses. His death was caused by having a red hot poker inserted into his anus through to his internal organs, so as to not leave a mark on his body.
Source: General Historical Texts