Catherine Howard - From my research I have found no evidence to support what happened in "The Tudors" at Catherine's execution but I feel that her wetting herself was simply to get us to feel sorry for her, a young woman who was terrified. Marillac’s report to the French King said that Catherine “was so weak that she could hardly speak”. However, Marillac was not present and an eye witness. Ottwell Johnson, wrote of her bravery, her “steadfast countenance” and her “constancy”. Also, Catherine, as Queen and higher in rank to Jane Boleyn, was executed first. She paid the executioner, forgave him and then knelt in prayer.Julia Fox, in “Jane Boleyn: The Infamous Lady Rochford”, writes of how Catherine then addressed the crowd, acknowledging her faults, stating her faith in Christ and asking everyone to pray for her. Contrary to myth and legend, and "The Tudors", Catherine did not cry out “I die a Queen, but I would rather have died the wife of Culpeper”, instead she was dignified and followed the usual convention of execution speeches. She was then executed with one blow of the axe.
Cromwell - Thomas Cromwell did suffer a botched execution but there is nothing to support "The Tudors" story that he was executed by a drunk paid by his enemies. Chronicler Edward Hall wrote that Cromwell "so paciently suffered the stroke of the axe, by a ragged Boocherly miser whiche very ungoodly perfourmed the Office" and the fact that he comments that the executioner was "boocherly" and that her performed his job badly suggests that it was botched and that it took more than one blow to sever Cromwell's head.