Demise

Demise (終焉の者) is one of the two main antagonists 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 significantly larger with a flamberge-esque edge, and being an overall darker color. His voice clips were done by Takashi Nagasako, who previously did voice clips for Ganondorf and Ganon.

Appearance
He is a demonic entity with a humanoid appearance. His skin is made of what looks like, dark scales, and in some parts bare with pale-gray. He wears a long, brown cape around his waist, embroidered with gold in a triangle pattern and held by belt. His head is covered in flames in place of hair, and has a white, glowing scar on his forehead from what could be the spike embedded in his head while being The Imprisoned. His facial features bear a striking resemblance to that of Ganondorf's. Although, according to Fi, Demise appears differently to everyone who see's him.

Biography
Prior to the events of the game, emerging from underground, Demise led a campaign to obtain the Triforce, having his minions destroy everyone and everything in their path to get it. However, Demise ends up being transformed by Hylia into The Imprisoned, a behemoth creature that was then sealed away within the Sealed Grounds. Ghirahim, Demise's sword, attempts to resurrect Demise throughout the course of the game, using Zelda's life force as she is an incarnation of the goddess herself.

But even without Ghirahim's help, The Imprisoned is able to break the seal on its own on a near regular basis. Once Zelda learns that she is the reincarnation of the goddess Hylia, she seals herself into a crystal and enters a deep slumber in an attempt to keep The Imprisoned at bay. Returning to the present, Link completes the Song of the Hero and obtains the Triforce. With the Triforce assembled, Link wishes for the destruction of Demise. This causes the Statue of the Goddess to separate from Skyloft and crush the sealed Demise below. Unfortunately, Ghirahim merely captures Zelda and travels back in time to revive Demise there, succeeding in doing so despite Link's best efforts to stop him.

Demise forces Ghirahim back into the true form of his blade while amazed to meet a living creature who shows the courage to face him. Impressed, Demise challenges Link to a battle, in which Link manages to defeat the malevolent being and restore Zelda's soul to her body. In his final breaths, Demise curses Link as he vows that his hatred will take a life of its own in new, endless cycles that both Link and Zelda's bloodlines will be a part of and live lives of darkness and sorrow. After Demise's body dissolves, his residual consciousness is absorbed into the Master Sword before the weapon is sealed away so the fiend can completely dissolve over time.

Demise's prophecy of the incarnation of hatred seems to signify the reasons for Ganon's existence and the tribulations that he causes for Link and Zelda's various descendants. It could also indicate connections with other beings of hatred throughout the series.

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