Q:

Latin/Greek for assassin

As far as I am aware, assassin comes from the Arabic حشاشين‎ (Ḥashshāshīn).  Clearly, the concept of murdering someone for either political or religious reasons was not invented by the Ḥashshāshīn. So, prior to the first crusade, what were assassins called in Latin/Greek?
The Oxford dictionary defines assassin as the action of assassinating someone and to assassinate as [To] murder (an important person) for political or religious reasons.

A:

"Assassin" doesn't really mean somebody paid to kill. It rather means somebody who kills a prominent person by surprise attack. (1, 2, 3)
Latin seems to have had a word for this: sicarius. I don't know if ancient Greek did. 

