Darkrai

Darkrai is a dark-type Pokemon from generation IV.

While it's abilities and looks make people think of it as evil, while in reality that's only some Darkrai and others are heroes such as in the Anime.

In Alamos town a Darkrai lived there and fought against Dialga and Palkia who trapped the city in another dimension which had various side effects all of which Darkrai was blamed for even though it didn't have those kinds of abilities. It sacrificed itself to slow them down, but when everything was restored, it was brought back to life as well.