Naruto and Kurama.
Naruto Uzumaki is the third jinchūriki of Kurama — the Nine-Tails. He is gifted with its enormous supply of chakra, to which Kakashi Hatake estimated it to be a hundred times greater than his own when its influence is not suppressed.[1] It also gives Naruto accelerated healing (recovering from minor injuries within seconds and major injuries within a day). Also, depending on the amount of Kurama's chakra he's using, Naruto is given an increase in strength, speed, and his healing factor are pushed to such levels that he completely recovered from a Chidori through his chest in mere moments with no lingering signs of injury.[2] At times, he is also granted a fox-shaped chakra shroud with massive invulnerability, being able to resist being pierced by Orochimaru's Sword of Kusanagi, a sword known as being able to cut through adamantine}}, and is completely undamaged by the alkali substance excreted by Saiken, which was able to damage Gyūki and disintegrate its surroundings rapidly.
Due to the Eight Trigrams Seal that his father, Minato Namikaze, the Fourth Hokage, placed on him, it had allowed a small amount of Kurama's chakra to always mix with Naruto's own. Kurama's chakra first came to Naruto during life-threatening situations, given to him by the fox itself to ensure its survival, but after training with Jiraiya, Naruto learned how to contact Kurama and demand some of its chakra. Alternatively, Naruto could give into his anger or frustration, allowing Kurama to force its influence upon him. Depending on how much he gained, Kurama's influence within its chakra could make Naruto lose control of his senses, devolving into an animal that attacks anything within reach, as well as damaging his own body, slowly shortening his lifespan. Although a number of methods had been devised to break its influence over Naruto (Jiraiya's seal tag,[3] and Yamato's Hokage-Style Sixty-Year-Old Technique — Kakuan Entering Society with Bliss-Bringing Hands, which was facilitated by Hashirama Senju's necklace Naruto wore before its destruction),[4][5] Naruto simply limited his use of Kurama's chakra, and tried not to allow his anger get the better of him, but he eventually attempted to exercise more control over it, in which he was able to achieve during the Fourth Shinobi World War.
After combining his chakra with Kurama's and recently developed a trusting relationship, Naruto and the fox can switch control of his body at will, allowing Kurama to speak through him.[6]