Most of the cases I have come across in my own reading feature assassins that are mostly opportunistic (i.e. have access to the target) or fanatical (don’t care about the personal consequences). The most high-profile cases of assassination throughout history seem to be wildly at odds with the cold, calm, professional characterisation they are often shown to have. Caesar, Franz Ferdinand, Oda Nobunaga, JFK, even the killings by the Order of Assassins don’t fit the bill. The assassins in these cases were essentially 'fire and forget' or just the people who had access to the target.

To clarify, I’m asking about the history of the image and portrayal of assassins, and where that comes from, and how rooted that is in reality – rather than what assassins were actually like.