Haghen, Hagano, or Hogni, may be considered as the villain of the Nibelungen.  In the Danish version he is the half-brother of Grimhild and Gunther, with an elf-father; in the German, he is their wise and far-travelled uncle, who first related the adventures of the newly-arrived stranger, Siegfried, but always seems to have disliked him, and readily undertook to revenge Brynhild's injuries upon him.  As Loki deceived Frigga, he persuaded his niece to mark where was the mortal spot on her husband's skin, and contrived that no wine should be taken into the forest, so that Siegfried might be reduced to lie down to drink at the stream, and thus expose the fatal place.
    The body bled at his touch, and he was the chief object of Chriemhilt's vengeance, more especially after he had taken the treasure away from her, placed it in a cave beneath the Rhine, and jealously guarded the secret of the spot.  When she invited the brothers to Hungary he was much averse to the journey, till he found that his disclination was imputed to fear, when he became vehemently set upon going, in spite of the omens against it.  Taunts and injuries passed between him and Chriemhilt, and and the next day the fierce and furious battle began, which raged till Gunther and Haghen alone were left.  After Gunther had been killed, Chriemhilt offered Haghen his life, on condition that he would disclose the place where the treasure was, but he refused, and died by her hand. (History of Christian Names, Yonge, 1885)