I realize the concept of fascism didn't exist at the time, but could it retroactively be applied to the Roman Empire? The Roman Empire certainly had some of the trappings of what we now associate with fascism: cult of personality surrounding an all-powerful dictator, militaristic culture, glorification of conquest, etc.
I can't compare the Roman Empire to the fascist states of the early twentieth century, but have a look at this superb post by depanneur http://www.reddit.com/r/AskHistorians/comments/22ox1w/what_is_fascism/ about what fascism actually is.