Nephrite (ネフライト Nefuraito) is the second of the Four Kings of Heaven to appear. Takeuchi describes him as cocky and emotional, writing in her concept notes he will probably get himself killed right off. He is the second-oldest, estimated at about 19 years old, and is in charge of the Dark Kingdom's North American division.:Act 3 He is named after the mineral Nephrite.
Nephrite's primary goal is to locate the Silver Crystal, but he also takes vows to exact revenge for the death of Jadeite. He uses a female "shadow" of himself to attack his victims, simultaneously taking control over their bodies and draining their energy. Makoto Kino kills him with her Jupiter Thunderbolt technique before any harm is done. Nephrite is briefly revived and is able to remember the Golden Kingdom and his time as a military officer of Prince Endymion before being turned into the stone from which his name was derived. The piece of nephrite (along with the stones for the other three Kings of Heaven) were kept by Mamoru Chiba and he used them to call upon his Kings of Heaven for advice.
In the first anime adaptation, Queen Beryl appoints Nephrite to continue the energy hunting job after freezing Jadeite. Nephrite hypothesizes that more energy can be taken by concentrating on a single human than by drawing from a crowd as Jadeite usually did which he said that it is one of the reasons why Jadeite had failed Queen Beryl. Establishing himself in an abandoned church, he uses intonation with the stars to detect the "energy potential" of individual people before attacking them when he implants the essence of one of his Monsters into a specific person's object. Nephrite's only disguise is "Masato Sanjouin" (三条院正人 'Sanjōin Masato'), a wealthy businessman and socialite. Over the course of his missions, Nephrite inadvertently attracts the attention and affections of Usagi's best friend, Naru Osaka, which interferes with his progress. When Nephrite discovers that Tuxedo Mask is Sailor Moon's weakness, Beryl orders Nephrite to destroy Sailor Moon. Despite being unable to destroy Sailor Moon, he siphons some energy from Naru earlier to Beryl. The Dark Crystal he crafts to detect the Silver Crystal reacts instead to Naru's love for him. Eventually, he comes to return her love and chooses to rescue her from Zoisite at the cost of his own life.
In the live-action series, Nephrite is Jadeite's main rival for the attentions of Queen Beryl, who considers him useless. His physical appearance is drastically changed, and he is portrayed as hot-headed and violent. Repeatedly humiliated by the Sailor Soldiers, and mocked by the other Kings of Heaven, he strives to win Beryl's favor, but she kills her as a demonstration of her power. He is then reborn in Tokyo as a normal human being with all his memories intact, getting a job at the karaoke parlor and forging a tenuous friendship with Ami Mizuno, who was compassionate toward him when she was Dark Mercury. At the end of the series, he is re-established with the other Kings of Heaven as one of Prince Endymion's guardians.
In Sailor Moon Crystal, Nephrite attempts to appeal to Queen Beryl to take Jadeite's place after calling him out for his failures only for Zoisite to intervene. Later, when his Soul Shadow is destroyed by Usagi, Nephrite rejoins the other Kings of Heaven to threaten the Sailor Soldiers. He then attempts to find the Silver Crystal by using a Monster who resembles a bride. However, he is attacked by Makoto and is forced to flee. In his past life, he was the love interest of Sailor Jupiter. He is killed by Metaria. He is the Knight of intelligence and comfort.
In the Japanese series, he is voiced by Katsuji Mori in the first series and in Crystal by Kōsuke Toriumi. In the DIC English adaptation, his name was changed to "Nephlite" and Maxfield Stanton, and he is voiced by Kevin Lund. In the Viz Media English adaptation, his voice is supplied by Liam O'Brien. In the live-action series he was portrayed by Hiroyuki Matsumoto, and was portrayed in the stage musicals by Toshikazu Seike and Karen Yoda.