Zant

Presumably, Zant was to be the next in line for the Twili throne, but the Twili had seen amibtion and a love of power in Zant, the same qualities which caused the Twili to lose their king which made the Twili decide Midna would be a more responsible leader. The decision made Zant disillusioned in the Twilight Royal Family, which, added onto the fact that he loathed the idea of the Twili as  prisoners confined to the Twilight Realm, drove him to desperation. In throes of rage and despair, he looked towards the heavens for an answer.

Ganon became his answer. Ganon's evil spirit, entrapped in the Twilight Realm, approaches Zant and offered to share his own power with him, more or less only fueling his own desire to return to the World of Light. Zant agrees to this dark pact and then proceeded to overthrow Midna, transforming her into an implike creature. He changed the rest of the Twili into Shadow Beasts soon afterwards and proclaimed himself "Twilight King," with the ultimate goal in mind of spreading the Twilight across Hyrule to make way for the Twili to return to the world that belongs to them. Zant invaded Hyrule Castle, easily dispatching the Royal Guards and sent the Hylian Princess Zelda the choice of surrender or the complete massacre of all people in Hyrule. Zelda, dropping her sword, reluctantly yielded to Zant's demand.

Soon after, Zant engulfed most of Hyrule in Twilight, a process to be reversed by Link. He later appears to Link after the Fused Shadows are collected. Zant ordered Midna to grant him the power Midna retained as the Twilight Princess. When Midna refused, Zant almost kills her with the light of Lanaryu and places a dark stone in Link's forehead, keeping him in a permanent wolf state. The duo would escape Zant yet their paths crossed again at the Arbiter's Grounds with Zant placing a dark sword on Stallord's head before leaving. Link eventually discovered Zant had shattered the Mirror of Twilight into four shards scattered across Hyrule.

When Link and Midna meet Zant in the Twilight Realm, he undergoes a change in behavior that contrasts the character that he displayed before. The reasons to this change are often debated by Twilight Princess fans, and many ideas have been drawn up as a result. The predominately embraced theory is that the character change symbolizes Zant's immaturity when it comes to ruling the Twili, as is displayed by his childish tantrums and fits. These qualities might actually indicate insanity borne from his anger, greed, despair, and desperation after losing the position as ruler of the Twili to Midna.

After Zant is defeated, he proclaims that he will be resurrected infinitely by his god, who is in reality simply Ganondorf and that the curse placed on Midna cannot be removed. Midna, hearing this speech, destroys him with a mere fraction of the power of the Fused Shadow.

At the end of the game, a vision of Zant's neck breaking directly proceed's Ganondorf's death. One may speculate that the magic of Twilight leaving Ganondorf's body along with the Triforce of Power stripped him of his power, and he was killed by the Master Sword.

Boss Strategy
Zant is one of the hardest bosses in the game, with the ability to teleport to previous battles and change assault tactics.

He will at first teleport both himself and Link to the Forest Temple boss arena and float above the poisonous water and shoot you with balls of dark energy. Block these with your shield and use your Gale Boomerang to knock him down while he tries to get more energy. He will bounce around and land on the ground, attack him with your sword. Repeat this a few times and he will be defeated in this area.

Next he moves to the Goron Mines mini-boss arena and continuously will keep jumping making the platform move down. Avoid falling down by using the Iron Boots when necessary. Eventually he will stop and attempt to attack you again. When he is tired remove the Iron Boots and quickly attack him. Repeat this a few times and he will be defeated in this area as well.

Next he moves to the Lakebed Temple arena. Be sure to equip your Zora Armor to breathe and your Iron Boots to sink to the ground. There will be multiple helmets like Zant's on the ground. One will open up and inside will be Zant and he will attack you. After he is done he will wait a few seconds before he closes the helmet. At this point quickly use the Clawshot to pull him out and attack him. He will go back into the helmet and you will have to figure out which one he is in and then repeat the process.



Next he goes to the mini-boss arena in the Forest Temple. He will jump around the pillars and first use your Clawshot to stun him, and then roll into the pole to knock him down, and attack. Repeat this a few times and again the arena will change.



He will go to the Snowpeak Ruins and jump around the area in a giant form. Hit him in the feet with the Ball and Chain to make him shrink down into a size that you can attack him with the sword. Repeat this a few times to go to the next area.

The final arena is just outside of Hyrule Castle, and Zant will now unleash two swords from his hands. With his two swords he has, he will simply start attacking you in a maniacal state, which you can either dodge this attack or Back Slice him. Occasionally he will do a spin attack and be left dazed for a few seconds. This is the best time to attack. After countless sword strikes, Zant will be finally defeated.

Miscellaneous
Zant bears an uncanny resemblance to Onox and Veran look on his clothes, and he has the same symbol Onox had on his armor. Given that Twilight Princess is full of references and close similarities to Oracle of Seasons, and Oracle of Ages, this is probably not purely by coincidence.

Not only does Zant's appearance resemble that of General Onox and Veran, but the Twili textures, shapes, and patterns can also show a similar cultural background to those who created Majora's Mask. However, a resemblance of clothing is not the only thing that reveals itself when analyzing Zant. His combat techniques, when facing him head-on, are similar to the techniques used by the several forms of Majora's Mask, Ganon, and Phantom Ganon. He brandishes his blades in a fashion that is just as devastating as the Majora's Wrath whips, teleports with a manner of cunning attacks, and uses consistent energy strikes in order to test Link's patience, just as Ganon and Phantom Ganon do.

An interesting theory has been made by a fanfiction writer with the alias of Triforce90, who has been dubbed by fans as the Zant expert and is currently writing Zant: The Life and Times of the Usurper King. He states that the source of Zant's character change is Ganondorf, who is trying to take full control of Zant's body at the time he meets with Link and Midna. According to Triforce90, Zant displays the body actions that people display when they are undergoing demonic possession as accounted in the Bible and cult classics such as "The Exorcist" and "The Exorcism of Emily Rose", where a victim will twist and bend into positions that are otherwise humanly impossible. Zant demonstrates these traits when he wraps his arms around himself and bends his spine back to face the ceiling at a 90-degree angle. He also undergoes a drastic voice change, which is similar to the voice changes of possessed people. Although the theory is soundly grounded and fits the dark theme of Twilight Princess, the majority of the fans still believe that Zant is merely being used as a comic villain in order to relieve the tensions of the moment.