666 was a number used in the book of revealtions to symbolise the number of the beast, it is also refered to as the letters of someone’s name or title, identifying the Antichrist.
This is all bull crap because when you study into the bible you don't take things as literal as fundamentlists and noobs. Because of incorrect translations the original number 616 was accidently reformed into the number 666 in the newer texts. During the origins of the apocalyptic writings, the romans were still in power and because of this The emperors were noted for their oppression of both Jews and early Christians. Both communities were known to use numerology, codes and symbols when living under Roman rule to avoid persecution and they according to the translation of 616 the name came up to be 'NERO' a roman emperor, other than this the term 'beast' and can only refer to a Roman emperor, specifically known as Domitian, and also because he had reigned during the proposed time of origin of the Apocalyptic writings, in addition his nickname beast was wideley known by the Romans, Greek, Christians and Jews.