The Naruto Franchise stands out with its distinctive set of abilities wielded by shinobi, which the series refers to as 'Jutsu'. However, even within this framework of chakra based abilities, some Jutsu are far too distinct, belonging to only a certain clan or bloodline. These one-of-a-kind abilities are known as Kekkei Genkai, and are renowned for exponentially enhancing a shinobi's fighting prowess.
While there isn't a limit to how many Kekkei Genkai a shinobi can use, even possessing one is considered a tremendous feat. It's quite rare to see two Kekkei Genkai wielded by one character, and only a few characters have been seen to possess that many in the Naruto series. However, one infamous Shinobi takes the lead in terms of possessing the most Kekkei Genkai – Madara Uchiha, with a whopping four Kekkei Genkai. While the methods of obtaining these powers may not be natural, simply being able to manipulate four distinct styles with ease is a feat in itself. With four Kekkei Genkai; Mangekyo Sharingan, Storm Release, Rinnegan, and Wood Release, no other Shinobi comes close to Madara's unfettered power.
Mangekyo Sharingan
An advanced version of the Uchiha Clan's Kekkei Genkai, the Mangekyo Sharingan gives the user access to a number of unfathomable powers, some that have even been classified as forbidden. Being a member of the Uchiha Clan, Madara already possessed the Sharingan, which later evolved to Mangekyo Sharingan. However, this elevated version of the Kekkei Genkai has one drawback; the usage of the Mangekyo eventually leads to the wielder losing vision in both eyes.
Madara, being the resourceful Shinobi that he is, found a way to bypass this drawback. To replace his own weakened eyes, Madara took the eyes of his younger brother, Izuna Uchiha, resulting in him gaining an even stronger version of the Mangekyo Sharingan – the Eternal Mangekyo Sharingan. This version of the Kekkei Genkai had no drawback, as he could use Mangekyo's power without any adverse effects, allowing him to become even stronger than before.
Storm Release
Storm Release is a Kekkei Genkai acquired by infusing lightning and water. Madara did not possess this power naturally, as he acquired the technique later on when he gained the chakra of the Six Paths. Madara's version of the Kekkei Genkai is slightly different, as he infuses his Storm Release with Senjutsu, resulting in a thin stream of light shooting from his mouth. This elevated version of the Jutsu is capable of slicing through mountains and cannot be dodged as it travels at the speed of light.
Wood Release
Wood Release is renowned as the rarest Kekkei Genkai in the shinobi world, as the only known user that achieved this power naturally was Hashirama Senju. None of his descendants were able to inherit this unfathomable power, and the only way to acquire this power is through infusing Hashirama's DNA with one's own blood.
Madara gained this power upon being brought back to life with the Reanimation Jutsu, as Kabuto had prepared a special vessel for Madara's reanimation, one that was infused with Hashirama's DNA cells. Since the First Hokage's DNA flowed through the reanimated body, Madara was able to freely wield the Wood Style Jutsu, adding another formidable Kekkei Genkai to his arsenal.
Rinnegan
The Rinnegan is said to be the strongest of the three most powerful Dojutsu, with no other Kekkei Genkai coming close to its visual prowess. Awakening the Rinnegan is a feat that is considered close to impossible, as the requirements are mostly unknown, and it cannot be passed down either. Madara awakened his Rinnegan by accident, when he consumed Hashirama Senju's flesh. As Hashirama's DNA merged with Madara's heart, he suddenly awoke the Rinnegan.
Shortly after gaining the Dojutsu, Madara passed away, yet he ensured that his return would be made possible before dying. One of his contingencies involved safeguarding the Rinnegan by secretly passing it along, which is how Nagato gained his Rinnegan. Upon being reanimated, Madara again possessed the same eyes, imbued with the Rinnegan's circular pattern. With such an unparalleled Kekkei Genkai at his disposal, Madara truly became a relentless force, as evident from the events that followed in the Fourth Great Shinobi War.