An epic is a long narrative poem.  Beowulf definitely meets that criteria because of its length. An Epic also includes a heroic story. An epic includes battles and war with. Finally an epic usually ends with the hero defeating the bad guy.

In Beowulf the hero was Beowulf by defeating the demon. Also Beowulf had heroic features a power and family bloodline. Beowulf also included the epic battle and epic has. Finally I think Beowulf is definitely an Epic as it fits the criteria.