So do you have a candidate in mind......who do you think it was or is? Does it not imply that it has to be a world wide figure that is recognizable for ALL the world to wonder after the beast who was, is not and yet is?.......?
So as you can imagine if a person lived in the year 2014 then ISIS is a current event and so it is by those who are alive +or- 40 years of this event going to be heavily debated prospect as to being ether the beast or the 10 horns. This makes sense because it's whats right in front of them currently and the mindset of mankind is that the beast is "always coming,in the future",,so things this way it tends to have one dismiss the past events and always train their energy on the things they think are going to happen(eg."ISIS is going to"),,that is everything is surrounded by what we think is future. So this will and always has caused a problem,a good example is Jesus himself and the Jews then present and their opinion of who Christ was(then present before their faces). As we know in their opinion(then present) Jesus was "not the Christ".
So they,then present when Christ was before their face(among them),not seeing he was Christ (looked forward)in time and was of the mind that(same as we see events as something future instead of present tense) saw Christ as a future event to themselves and did not consider that it could have been taking place right in front of their faces. We do the same today we attribute every thing we cannot figure out as (future),we consider our own selves as though we are so intelligent that it is impossible that we are deceived and will ever need to rethink the past and acknowledge the possibility that we have missed the meanings of anything.
I will give a very good past example(not to distant),but never the less there are very few who can remember (it) today,because it is a fixed event only those then alive would have witnessed. In the old days mankind looked forward in time and saw the beast and Israel as future tense to themselves then alive,that is from the destruction of Israel/temple in July 70ad and the then new Book of Revelations all these events were to them(then present) realized as a (Future tense reality),so they from that point have pondered the temple in Israel the Israeli government the beast ect.ect as something that will be fulfilled at some point in the future,and this continued until the modern days(our present).
In the 1500's till the 1900's there was not a "state of Israel" that the bible commentators could reflect on so all of the commentaries will reflect the opinions of the writers as though Israel was future tense (it was not there until 1948) so every thing they wrote will be of the future fulfillment of the regathering of the Hebrew people into the holy land by Jesus at his second coming(they had no Idea Israel would become a nation in 1948),so all of their works will reflect this.
I was born in the cowboy days(lol,not rally),but close enough that is when I grew up their were books written by men in the little boxes behind the pews from authors like b,w,Johnson B.W. Johnson (1833-1894)