Demise

Demise is a major antagonist of The Legend of Zelda: Skyward Sword. Interestingly the sword he wields resembles a corrupted version of the Master Sword, its hilt being the same general shape, but with a different design to the "wings" that make up the handguard, the triforce engraving being inverted, the blade being signifigantly larger with a flamberge esque edge, and being an overall darker color.

Biography
Prior to the events of the game, Demise sought to obtain the Triforce, but was sealed away by the Goddess. During Link's quest, Demise is found in the form of The Imprisoned, a behemoth creature that acts as Demise's seal. Ghirahim is attempting to resurrect Demise throughout the course of the game, using Zelda as a vessel.

During the final battle, of which Demise is the boss, Link manages to defeat the malevolent being. In his final breaths, Demise curses Link, informing him that an incarnation of his hatred will be born in new cycles with no end and that Link and Zelda will be a part of these cycles. This incarnation of hatred will always be drawn to Link and the Master Sword, forcing the hero to live lives of darkness and sorrow. Once Demise finishes speaking, he is absorbed into the Master Sword where he is sealed away for eternity. This prophecy of Demise's incarnation of hatred seems to signify the reasons for Ganon's existence and Link and Zelda's perpetual reincarnations.

Entymology
Demise is a word that generally means either the end of something, usually a life, or the death of a significant person.