Nine-Tailed Demon Fox

Name: Nine-tailed Demon Fox, "Demon Fox", English TV "The Nine-Tailed Fox Spirit/Demon"
Creature type: Kitsune (Fox)
Host: Naruto Uzumaki
Unique traits: Near-limitless chakra, incredible strength
Status: Active, sealed in host
The nine-tailed demon fox is a truly powerful beast; a single swipe of one of its nine tails can raise tsunamis and flatten mountains. After the demon fox attacked Konohagakure, the Fourth Hokage sealed it into the newborn Naruto by using the Dead Demon Consuming Seal, sacrificing his own life to do so.