Analysis
When examining Shahrayar from A Thousand and One Nights as a monster alongside Zahhak from the Shahnama their stories are able to align and reveal more about Shahrayar. First, both of these kings were humans who commited acts that were deemed evil. In doing so they were both examples of what a bad king looked like, as they both became hated by their subjects for disregarding their subjects wellbeing. This draws in the possible consiquence that Shahrayar would have faced and shows how he was a monster but then changed to become human again, unlike Zahhak who fell to his monstrous side.
Looking at this difference between Shahrayar and Zahhak reveals that the monstrous side of humanity needs a ritualistic "feeding", in the form of killing subjects, to grow inside and overtake the humanity. Zahhak killed everyday without stopping and created his own downfall because of this. Shahrayar on the other hand, was interrupted. Similar to the proverb in which there are two wolves inside everyone, one good and one evil, Shahrayar stopped feeding the evil wolf and the good was able to over power it yet again.
Looking at the stories told within A Thousand and One Nights itself, Shahrazad tells these stories trying to get Shahrayar to reflcet them onto himself and see that even monsters are capable of my humanity than he is. In each story the Djinn, seen as monsters with only bad intentions, decide to spare the person they had previously sworn upon. Here Shahrazad is able to both spare herself another night, and show Shahrayar just how evil he is by showing that he has commited more monstrous acts than an actual monster.
Finally, looking towards the object depicting Iskandar, we can see that it is possible for a king in power to not succumb to the temptations of evil and stay uncorrupted. Iskandar left behind a great legacy, having completed many accomplishments and gathering love from all his subjects. (Stock) Iskandar tries to preserve his legacy by gathering everyone who would threaten it and killing them, a mass genocide that would create as large a death toll as Shahrayar and Zahhak had accumulated over time, but he was talked out of it and able to see reason. He was able to see reason because he had not yet fed his monster, he was still full of humanity. This is just as important as Shahrayar's comparison to Zahhak because this shows that humans are able to keep their inner monster at bay, but once it takes over it is far more difficult and time consuming to get control of again.
The stories of Shahrayar, Zahhak, and Iskandar show that the monsters hidden within humanity present far more danger than the physical monsters because of their constant need for evil and difficulty of stopping them.