Kurama (九喇嘛, Kurama), more commonly known as the Nine-Tails (九尾, Kyūbi), is one of the nine tailed beasts. Centuries of being regarded as a mindless monster and sought after as a tool for war caused Kurama to hate humans. After being sealed into Naruto Uzumaki, Kurama attempts to maintain its negative opinions about the world, but with Naruto's insistence on treating it with respect, the fox overturns its hatred and willingly strives to use its power for the world's salvation.
He is voiced by Tessho Genda in Japanese and Paul St. Peter in English, the latter of whom also voices Leomon, SaberLeomon, Apocalymon from Digimon Adventure, Cherubimon, Diaboromon from Digimon: The Movie, Wormmon, Stingmon, Tapirmon, Paildramon and Imperialdramon from Digimon Adventure 02 in the English Version and Tritor in Power Rangers Zeo.
Kurama is a kitsune with nine long swiping tails. It has red-orange fur with black fur around its eyes that stretches to its ears, red irises with black slits for pupils and the upper-body structure of a human, complete with opposable thumbs on its clawed hands. During the last remaining days of Hagoromo, Kurama was much smaller in size, but still dwarfing the Sage. Its overall appearance was leaner and softer while less-defined in shape with a rounder face, akin to a fox cub. Over time, Kurama's size increased tremendously, roughly equaling the Hokage Rock, and Gamabunta being only the size of Kurama's torso. Its pupil alone is bigger than a tall human. When Minato separated Kurama's Yin chakra and Yang chakra, it was split into two entities, both of which are shrunken more than half its original size, yet still roughly the size of other massive tailed beasts. While the two are basically identical to the other, Yang-Kurama retains its original colouring while Yin-Kurama is darker coloured.
Kurama is known being cynical, arrogant, and shrewd individual, along with a somewhat twisted sense of humor. It uses "washi" (ワシ) when referring to itself, which is generally used by older men. Its arrogance was shown on his belief where the strongest tailed beast supposedly the one with more numerous tails, which is disapproved by Shukaku. But its arrogance does have its limits though, as it claimed that it was unlikely to it to stand a chance against Ten-Tailed Beast alone by itself. However, it does easily get annoyed when Naruto uses a power other than its own, claiming its jinchūriki needs no other power than its own. It is also shown that Kurama deeply cares about Hagoromo Ōtsutsuki, viewing him with great respect and even shed tears after the Sage had imparted his final words to them.
Perhaps as results of humanity's negative treatment on him, he became bitter as seen in the beginning of the series, even going as far as proclaiming itself to be the living embodiment of hatred like what everyone believed. Ever since his imprisonment, it will do whatever it takes to free: Triest to kill Naruto's parents before sealed completely inside their child out of desperation (though Obito, whom mastermind it's rampage in Konoha freedom mostly blamed for this and Kurama more like the scapegoat instead the killer) and manipulate Naruto for too dependant with it's chakra instead his. This ultimately backfires when Naruto ultimately stripped most of his chakra in the end, and also locked him with improved seal. However, in spite of his manipulation, he does have respect for Naruto and his determination. He also once warned the immense hatred inside Sasuke (though was only a ruse that backfires once again and Naruto retaliates by saying that he will do something that will change it someday). After having witnessed all of the challenges and endeavours Naruto had in his life, and Naruto succesfully freed Son Goku from Obito's control, it finally became convinced of Naruto's word and offered to meld its chakra with his as a coalition, to which Naruto then removed the seal that restrained it and happily acknowledged the fox as his team-mate and a member of Konoha. Kurama is afraid of Himawari Uzumaki when he was knocked out due to her Gentle Fist on his and Naruto's chakra point.
All in all, two things are clear about Kurama: First, Kurama is merely a bitter and symphatetic bijuu who wished to treated as person instead of tool as well as capable to perform good deeds as he proved through its jinchuuriki friend Naruto, and second, the belief where it being composed of malevolence and chakra that merges into nine-tailed fox-like kaiju is hoax and superstitions made by those who despised him in the past stemmed from his reputation and power.