In the MCU/Marvel with the Omnitrix/Ultimatrix - Chapter 53: Guilt

Lives are a currency, and Noah Vines is rich.Reincarnated into the body of a poisoned magic school professor, Noah is given more than just a second chance at life. Every time he dies, his body reforms. With infinite variations of runic magic to discover and with death as a painful soul wound rather than a final end, Noah finally has a chance to wander the lands of the living once again. And this time, he plans to get strong enough to make sure that he never has to wait around in the afterlife again.

Before her rebirth, Wei Luo was an innocent little girl.

After rebirth, she appeared lovable on the outside but was a different person on the inside.

Those who learned of her true nature yielded to her.

Only the prince regent regarded her as a treasure; no matter how much he pampered her, it was not enough for him.

Anything she wanted, he gave her, including the princess position that she didn’t want, which he stubbornly pushed onto her.

- Description from Novelupdates

Died a Hero, Reborn as a Demon...

The strongest Hero in the world killed the Demon King, the most powerful demon ever to appear on Earth. He achieved something which no other hero could ever do.

But alas, the Hero never expected his own girlfriend, his own friends, and the organization he trusted to suddenly turn against him and try to kill him.

It was the cruelest blow he was ever dealt in his life.

He still didn’t give up and tried to stand his ground, but they had come prepared, and he was caught unawares in their trap. He fought to his death only to find himself transmigrated into a demon’s body!

But who would have thought that he would be the husband of the Demon Queen!

However, life as the royal consort was not easy at all. So read to find out how he is going to overcome those trying to step on him and finally get his revenge.

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Eight hundred years ago, Xie Lian was the Crown Prince of the Xian Le kingdom. He was beloved by his citizens and was considered the darling of the world. He ascended to the Heavens at a young age; however, due to unfortunate circumstances, was quickly banished back to the mortal realm. Years later, he ascends again–only to be banished again a few minutes after his ascension.

Now, eight hundred years later, Xie Lian ascends to the Heavens for the third time as the laughing stock among all three realms. On his first task as a god thrice ascended, he meets a mysterious demon who rules the ghosts and terrifies the Heavens, yet, unbeknownst to Xie Lian, this demon king has been paying attention to him for a very, very long time.

- Description from Novelupdates