Cromwell AND Popes for this one.
Formosus was put on trial during the Cadaver Synode, not only two years after he died, but also for accusations levelled twenty-five years earlier, for which he had been excommunicated back then, but then also reinstated, and obviously elected Pope in the meantime.
Also some fun facts about Cromwell’s head, which you probably were aware of already.
There may or may not be a third part to this, covering yet more exciting historical trials.
eta: Charles II, obviously, not Charles V. That teaches me to have bad handwriting.