Very well put!"You must understand this: I have a particular set of skills, and I will use them on you if you do not give me my daughter back"
- Liam Neeson, Heroic Assassin
It seems to me as if some people have confused the assassin with some kind of fictional ninja who is clad in black, kills because he's told to, and slices open his target in a single moment.
But all it really means is somebody who's going to kill some prominent figure.
Can the assassin be a heroic character? Or, will he always be a mercenary at best and a cold-blooded killer at worst? Or are they anti-heroes, like the Punisher? What are some good examples of some heroic assassins?
... it seems that for the most part everyone has seemed to forget that a sniper is an assassin. Even though in D&D most snipers are rangers (for obvious mechanical reasons, specifically the track and bow proficiency) a sniper is one who "studies, stalks and eliminates" any known threat. While the popular conception is a Soldier on the battlefield taking out targets of opportunity, snipers can and have (look it up) posted a target for weeks before they "take the shot".
The sniper school teaches the art of the stalk which an take a very LONG amount of time to complete. They are, at the core assassins, ones that have to live for the rest of their lives knowing what that entails. ... However, I have never met a hero that has ever said..."I'm a hero!!". ...
I happen to know a couple "ex" snipers and you can trust me, they have issues - they never think of themselves as heroes, just people doing the job they were taught, the best way they know how. ...
Someone who has to spend half an hour whaling away at someone until their HP are gone isn't much of an assassin!)

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.