Who helps Beowulf kill the dragon?

Wiglaf helps Beowulf slay the dragon.  During the battle
with the dragon, all of Beowulf's men, except for Wiglaf, run away. Wiglaf sees that
Beowulf is being overcome by the dragon, and though Beowulf had stabbed at the dragon
with his ancestral sword, Nagling, the sword had broken.  The dragon is able to bite
Beowulf's neck with its poisonous fangs.  Wiglaf realizes that stabbing the dragon in
the head, as Beowulf has tried, would not work, so he struck lower down, in the dragon's
belly.  He had to plunge his sword all the way into the dragon, burning his own hand,
but he managed to kill the dragon.  Since Wiglaf was the only soldier who did not break
comitatus and run from the battle and because he'd always been loyal to Beowulf, Wiglaf
was rewarded.  Beowul told Wiglaf that he should be the next king since Beowulf knew
that his own time was quickly drawing to a close.