"The alien behind the legend" is presented as a research work, a comparative investigation between events and characters from folklore and what characterizes the religious texts of ancient civilizations. It also goes through a further "step" of comparison that brings out other surprising similarities with the more recent "Theory of Ancient Astronauts". Is it possible that behind the tales handed down by our ancestors and those heard by our more direct ancestors that refer to encounters with fantastic creatures there is more than just a vivid imagination? Are we really supposed to believe that this attitude is correct and useful? In doing so, are we not sinning in pride? Instead, it should be our duty to reconsider all the evidence and concentrate on finding that part of the truth that all legends are said to contain.