I’ve always thought that Guy Fawkes’ Night is one in the eye for James I, rather than for old Guy himself.
There’s an old Punch cartoon that satirises the contemporary pen-portrait of all the conspirators - it shows them in the same suspicious-looking group, complete with 1600s-style goatees and big buckled hats - saying, “Gunpowder, Treason and Plotte! And we all go Wearing these Funny Hats?”
I’m inclined to agree about Ireland. I clued myself up a little recently with a long read through the Encylopædia Britannica essay on Irish history, and came away with the impression that the place has been a mess since forever, and it’s harsh to attribute too much of it to Cromwell. Still and all, let’s not forget that Cromwell dealt pretty high-handedly with Parliament in his own turn. I’m struggling to think of any major political reforms originating from the Commonwealth that have led to benefits since, though anyone’s welcome to educate me.
Haw-Haw was a scuzzbucket, no error, but it’s doubtful that he actually achieved much that was ill, though he gets points for trying.
My nomination, though not necessarily destined to make the cut, is Matthew Hopkins, the Witch-Smeller Pursuivant (sorry, channelling Blackadder again there: that should be “Witch-Finder Generall”), who managed to find an awful lot of witches by the most dubious of means…
Well, I for one despise the guy for failing in his task!
He is generally acknowledged as “the last man to enter Parliament with honest intentions” 
See what I mean about the perverse admiration bit? 
