Danzo could be a main antagonist. He's always been power - hungry and has seen Naruto as a threat to his control over the village. After Pain's attack, he seizes the opportunity to turn the villagers against Naruto.
The villagers themselves could be antagonists in a sense. Their fear and lack of understanding lead them to betray Naruto. They don't see his sacrifices but only the destruction that happened during Pain's attack.
The village elders could be the main antagonists. They might see Naruto's godlike powers as a threat to their traditional way of ruling the village and decide to get rid of him. Another option could be a secret organization within the village that wants to use Naruto's power for their own evil purposes and when he refuses, they turn on him.
Some of Naruto's former friends who have been influenced by the negative propaganda against him could also be antagonists. They might be misled into believing that Naruto has changed for the worse. They could actively oppose Naruto, either by trying to capture him or by preventing him from doing certain things. Another possibility is that there could be a hidden group within the village that has a vendetta against Sasuke and, by extension, Naruto for bringing him back.
Obviously, the gods themselves would be the main antagonists. They have the power to manipulate Naruto's world and his fate. They could be some sort of ancient deities who have been watching over the ninja world from afar and now feel the need to interfere.
The elders of Konoha could be the main antagonists. They are often shown to be power - hungry and willing to do whatever it takes to maintain their control over the village. They might see Naruto as a threat to their authority and decide to betray him. Another possibility is Danzo. He has always had his own agenda and has been shown to be ruthless in achieving his goals. He could easily be the one behind the betrayal of Naruto in a fanfic.
Well, sometimes the antagonist can be an internal struggle within Ash or May themselves. For example, Ash's over - ambition to become the best Pokémon trainer might lead him to make choices that seem like a betrayal to May. His single - minded focus on winning battles and collecting badges could make him neglect May's feelings. In this case, Ash's own ambition is acting as the antagonist in the story. Similarly, May's insecurities could make her misinterpret Ash's actions as betrayal, and her insecurities then become the antagonist in the relationship.
The Akatsuki remnants could still pose a threat. Members like Sasori or Deidara might have had backup plans or followers who now want revenge for the Akatsuki's downfall. They could target Naruto specifically, seeing him as the one who brought down Pain and disrupted their plans.
Maybe Orochimaru's former followers who are still lurking in the shadows. They see Naruto as a threat and Hinata as an easy target to get to Naruto. Another possibility could be some power - hungry shinobi from other villages who view Konoha as weak after the Pain incident. They might target Naruto and Hinata as key figures in Konoha's future to try and undermine the village's rebuilding efforts.
One possible plot could be that the village, still shaken by Pain's attack, blames Naruto for not preventing all the destruction. They think he has some hidden connection to Pain and turn on him. Naruto, heartbroken, decides to leave the village and find out the truth about his past and the Akatsuki on his own.
It could also be that the Olympian Council as a whole acts as the antagonist. They might have made decisions that Percy sees as a betrayal, such as sacrificing the safety of demigods for their own political gain. Each god on the council, with their own self - interests, might contribute to Percy's feeling of betrayal, making the council as a whole the main force he has to oppose.
Well, the main antagonists could be a group of rogue ninja who are hired by a powerful nation to take down Naruto. Since he is unkillable, they would have to use more underhanded tactics like trying to isolate him from his friends and allies. Or perhaps there is a dark force that is awakened by Naruto's unkillable state, thinking that he is a threat to the balance of the ninja world. This dark force could then become the main antagonist, trying to destroy Naruto at all costs.