Astor

is the secondary antagonist of. He is regarded as a seer by the HWAoC: for his predictions of the future, and guides the Yiga toward their common goal of the HWAoC:.

Biography
Very little is known about Astor's life before the events of. All that is known is that he was raised in a village in Hyrule, and that he eventually became a powerful sorcerer and a follower of Calamity Ganon and would later align with the Yiga. Shortly after a future HWAoC:, a miniature Guardian created by Zelda when she was young, travels to the past, the HWAoC: that followed him possesses the dormant past Terrako, forming HWAoC:. At some point Astor found Harbinger Ganon and used it to see into the future, setting his grand plan of destroying Hyrule into motion.

Astor first appears after the defeat of HWAoC: in Gerudo Town, disappointed at the Yiga leader's incompetence. He then views a glimpse of the future through Harbinger Ganon, stating that he will not allow anyone to alter the course of the future.

The seer makes himself known to the Champions of Hyrule during their visit to the Lost Woods, where he summons HWAoC: clones of the Champions, called Hollows, to attack them. He then appears at the foot of the Great Deku Tree, commanding the Hollows to kill Princess Zelda. However, he is quickly defeated by Link, who retrieves the Master Sword from its pedestal.

After HWAoC: begins to reactivate the Sheikah Towers, Astor commands the Yiga to prevent the final tower from being activated, as it would reveal their location to the Champions. He then explains how Harbinger Ganon is a fusion of Terrako and Calamity Ganon, and that he will use its power to bring the world to its knees - a statement that HWAoC: deems foolish. His orders to the Yiga clan end up unfulfilled, as the Champions are able to reactivate the final Sheikah Tower and take control of the Yiga Clan's hideout. Enraged that the seer would allow this to happen, Sooga grabs him by the neck - however, Astor calmly explains that their defeat was ordained by fate, and that if the Yiga were to harm him they would make themselves enemies of Calamity Ganon.

Soon after Calamity Ganon awakens and Hyrule Castle is taken over, Astor betrays the Yiga Clan and kills large numbers of their footsoldiers, using their life energy to revive the Blight Ganons, who failed to kill the Champions like they were supposed to. He tells a horrified Kohga and Sooga that by becoming a blood sacrifice to Calamity Ganon, they will finally become useful, summoning a Hollow of Link to do the deed. Kohga begins to run, but changes his mind and decides to stay and fight alongside Sooga - however, their battle ends with Kohga fleeing to seek assistance from Princess Zelda and Sooga presumably being killed.

Astor appears again during the battle at Fort Hateno, where he summons the Blight Ganons to attack Zelda. Link attempts to fight them off, but is quickly overwhelmed. Zelda, desperate to save Link, awakens her sealing power and incapacitates the Blight Ganons, allowing Link to destroy them once more while Astor flees.

As the Champions reclaim Hyrule and begin infiltrating Hyrule Castle, Astor makes his final stand against them alongside Harbinger Ganon itself, ranting that as Calamity Ganon's right hand it is his destiny to destroy Link and his allies. The two are defeated, and as the Champions close in on them Astor attempts to command Harbinger Ganon to destroy them - however, his efforts are cut short as he becomes consumed by Malice, screaming in agony as Harbinger Ganon absorbs him into itself and uses his power to transform into its true form - Calamity Ganon.

Trivia

 * Astor is similar to Agahnim from The Legend of Zelda: A Link to the Past, both being sorcerers/religious figures bent on reviving Ganon and fighting with energy ball attacks.
 * However, while Agahnim is Ganon's alter ego, Astor is his own character, similar to manga deceptions of the evil wizard. Fittingly, both are killed by Ganon when he has no more use of them, though in Astor's case, he is absorbed to be Ganon's new body.
 * Astor also is similar to Ghirahim from The Legend of Zelda: Skyward Sword, both being characters bent on reviving their master (Ganon in Astor's case, and Demise in Ghirahim's case), and having little tolerance for their henchmen, and even proceeded to end up killed by their master shortly after their revival.
 * A notable difference between the two, however, is that Ghirahim was completely willing to die to resume his status as Demise's sword, while Astor was unaware of Ganon's intentions of absorbing him and is appropriately terrified when it happens.
 * Although the exact events of are not applicable to  and its sequel due to the split timeline caused by Terrako, it is implied that Astor does exist within the original game's past events. It is possible that he may be the fortune teller mentioned in Zelda and King Rhoam's diaries during the events of Breath of the Wild, but not enough information exists to confirm this.