Who could be the main antagonist in a 'Naruto dies and is reborn' fanfiction?

It could be a new character created just for the fanfiction. Maybe a rogue ninja who has mastered a dark and powerful jutsu that Naruto has no defense against. This antagonist could be seeking revenge on Konoha for some past wrong and sees Naruto as the biggest threat to his plans.

It could be someone who was secretly behind Naruto's death in the first place. Maybe a rogue ninja who has a vendetta against the Hidden Leaf and saw Naruto as a major obstacle.

It could be Orochimaru. Since Naruto was a potential threat to his plans in the original story, if Naruto died as a baby, Orochimaru might be able to carry out his experiments and schemes more freely without having to worry about Naruto interfering in the future.

It could be an unknown shinobi from a far - off land. A shinobi with powers that Naruto has never encountered before. This new antagonist might have some dark and powerful jutsu that Naruto simply isn't prepared for, which ultimately leads to his downfall on the bridge.

It could be a new, powerful Titan that was previously unknown. This Titan might have a vendetta against Percy specifically, seeing him as a major threat to their plans. Maybe they manage to kill Percy, but his rebirth sets in motion a series of events that will lead to their ultimate downfall.

A rogue ninja from another village could be the main antagonist. Maybe a ninja from the Hidden Mist Village who has a personal grudge against Konoha and sees Naruto as the symbol of Konoha's strength. So, he devises a complex plan to take down Naruto. This ninja could have some unique and deadly jutsu that Naruto has never faced before, which ultimately leads to his downfall.

Madara Uchiha could also be a main antagonist in this fanfiction. He has grand plans for the ninja world and the released Kyuubi could be a key part of his scheme. Since Naruto is dead and can't oppose him, he might try to use the Kyuubi to reshape the world according to his vision. He has the power and the ambition to be a major threat in this situation.

It could be a long - lost relative of one of the old villains like Orochimaru. Maybe this person has been in hiding, training and growing in power, and now wants to take revenge on Konoha for what happened to their family member.

It could be a rogue ninja who has mastered a forbidden jutsu and wants to destroy the village out of revenge. Naruto would then have to face this extremely powerful foe and in the end, sacrifice himself to stop the destruction.

Perhaps a new, unknown force. With Naruto gone, a previously hidden group with a vendetta against the ninja villages could emerge. They might blame the villages for the destruction caused during the war and see Naruto's death as the perfect time to strike, when the villages are still recovering and vulnerable.