Beowulf is the epitome of the epic poem. Its protagonist, Beowulf, possesses many characteristics which define him as a true epic hero.
Beowulf enters into the text "in the midst of turmoil." He comes to the Danelands after hearing about Hrothgar and his troubles with Grendel. Grendel has already murdered many of Hrothgar's men and forced the closing of Heorot (Hrothgar's mead hall). Traveling to the Danelands in the first place also illustrates Beowulf's desire (and heroic trait) of helping others.
Beowulf possess both arete (excellence) and aristeia (finest moment in battle). Both his arete and aristeia are illustrated and proven through Beowulf's battle with Grendel. Beowulf, not wanting to have an upper hand over the beast, decides to fight him without any weapons. This levels the playing field (makes the battle equal). Since both Grendel and Beowulf both possess the strength of thirty men, the fight must be even for Beowulf to prove his aristeia and arete.
Bewoulf's journey into Grendel's mother's lair depicts his figurative journey into the underworld. Every epic hero must make a long journey which, at one point, leads him into the underworld. In Beowulf, his journey from the Geatlands to the Danelands to the underworld proves a long journey is made (and it takes him into the underworld).