Revelations is prophecy, which is a foretelling of future events, and it should be taken literally whenever possible. Many believe that the two prophets are Enoch and Elijah. The bible says ALL men must see death and these 2 are the only men that have been translated or taken up into heaven without dying first.
Revelations is an allegory. It is not meant to be taken literally. Here's a riddle for you. What do we all know is coming, but never know the time? What could possibly have happened during the apostle's lifetimes, that has yet happened in ours? Death is the answer. We need to be vigilant in our faith, not for some big horrifying end of days, but for our own end of days.