Raiju

Raijū (雷獣,"thunder animal" or "thunder beast") is a legendary creature from Japanese mythology. Its body is composed of lightning and may be in the shape of a cat, fox, weasel, or wolf. The form of a white and blue wolf (or even a wolf wrapped in lightning) is also common. It may also fly about as a ball of lightning (in fact, the creature may be an attempt to explain the phenomenon of lightning). Its cry sounds like thunder.