The bible was written, in it's original form, in Ancient Hebrew and the number given to the beast in Ancient Hebrew was נרון קסר or "Nrwn Qsr" or translated from that Latin to modern English "Nero Ceasar", making Nero the "beast" or "Anti-Christ" refered to.
Nero was a Pagan Roman Emporer, he was judged by the followers of Christ to be against (or "Anti") Christ possibly as a result of him murdering his brother, mother and pregnant wife, castrating and marrying a man and using Christians as "human torches" to light his gardens at night.
Note: You can't actually translate the original "number of the beast" into modern numerical form, those that have tried rerturn with the result 616
If you wanted to play conspiracy theorist though, you could take the letters of the Hebrew Alphabet and their corrosponding numerical value as done to reach the 616 value and return a value of 666 from the name of a certain President of the United States.
Wow, I just realized how acutely boring I really am.
Edit: Apparently, Hebrew isn't supported by the BB's encoding, hence the wrong formation of נרון קסר