The Edward II story has been debunked, but it’s too, er, bizarre to let go. Here’s Wikipedia:
With Mortimer's execution in 1330, rumours began to circulate that Edward had been murdered at Berkeley Castle. Accounts that he had been killed by the insertion of a red-hot iron or poker into his anus slowly began to circulate, possibly as a result of deliberate propaganda; chroniclers in the mid-1330s and 1340s spread this account further, supported in later years by Geoffrey le Baker's colourful account of the killing. It became incorporated into most later histories of Edward, typically being linked to his possible homosexuality. Most historians now dismiss this account of Edward's death, querying the logic in Edward's captors murdering him in such an easily detectable fashion.