Rauru is a very important character in The Legend of Zelda: Tears of the Kingdom and despite never seeing him before, he’s not technically new to the series. A character of the same name was a sage in Ocarina of Time and it is very possible that he appeared to be human to the Hero of Time in order to not shock him.

Either way, when Ganondorf is reawakened he is the one that saves Link from certain death.

And gives Link his arm which he didn’t really need because he’s already dead anyway.

In a very fated time travel, Princess Zelda meets him and discovers that he was her ancestor. I’m not quite sure how things really worked for him and Queen Sonia in the bedroom and I really don’t want to know.

But he was technically the first King of Hyrule and very powerful.

Despite the warnings of his descendant Princess Zelda about Ganondorf, he takes a surprisingly diplomatic turn with him until the Demon King kills his wife and becomes even more powerful.

And when him and his friends can’t stop the Demon King, he decides to use magic at the expense of his life to seal Ganondorf away until there will be hero centuries later that would strong enough to stop him.

And he picks right with Link. Hopefully having a very peaceful after-life knowing that he saved the day indirectly.