Badass characters who get forgotten

I feel there are so many folk who either excel early on and then faded into the background, or who were antagonists that only failed due to very specific reasons. Who is your favorite? Mine will always be Kimimaro. He had a very hard life, was sick as hell. And he had one of the craziest kekkei genkai out of anyone in the entire series including filler and it was OG Naruto. I feel like someone could have pulled that out in the last war arc (having never seen that ability before) and people would have lost their minds