In Revelation 13.18 the number of the beast is 666. The verse also says that the wise with understanding could calculate the number and thus know the person it stands for. Who is it?
How you answer any question from the Revelation depends on how you understand the book in general. If you think the letter is a road map to the future, ala Hal Lindsey, the number of the beast is attributed either to a contemporary or someone in the future. In the recent past the beast, generally thought to also be the anti-Christ, has been assigned to the Pope, Hitler, Nixon, and Kissinger to name just a few.
However, when John wrote this letter to the seven churches in Asia Minor he likely had a contemporary figure to his day in mind.
To understand the number = a name we have to know a bit about Hebrew, Greek, and Latin. These three language systems do not have a separate set of symbols to stand for numbers as we do. Instead, the languages used letters. The best modern example is Roman (Latin) numerals which are still used in the copyright date of movies. (MCMLXVII=1967). The letters of someone's name added together become a sum total. To solve the riddle of 666 we add the value of the names of possible suspects in Latin, Greek, or Hebrew and try to guess to whom John was referring.
Most modern scholars have begun with the most obvious "beast" of John's day, Nero, who fervently persecuted the Christians during his reign. In Greek, Nero's name adds up to 1.005, but when the name is transliterated into Hebrew it equals 666. Personally, this is my favorite solution, but it is not without flaws. One flaw is John could not be sure folks would know to put the name into Hebrew. The temple in Jerusalem had already been destroyed by the time John wrote this letter and Hebrew was seldom spoken, except in the more orthodox Jewish communities. Remember, John was writing to seven Greek-speaking churches in Asia Minor.
However, there are other clues that seem to point to Nero. According to Revelation 13.1-3 the beast receives a mortal wound in battle, but is resurrected to fight again. After Nero died in 68 there were rumors he was not actually dead, but that he had gone into hiding in Parthia to the east to await time to resurrect his throne in Rome. Three impostors actually came forward claiming to be Nero and two were well received in Parthia as possible leaders.
But who is the definitive 666? No one really knows for sure. Theories abound incriminating nearly every political and religious leader across time. However, I read the Revelation as a letter of hope written specifically to seven churches in Asia Minor during the first century. From these words, written to men and women of faith, I too can draw hope that God will be victorious in all things in all times even over one called the beast.