The King has a large, globe-like body mass that is suspended in the air with chains. He has a skull head, which is recessed within a larger, outer skull-like formation. He has four arms that hang from his body, each with only three claws on each of his "hands."
Many Shinigami refer to him as the "Old Man," and Death Note 13: How to Read says that he "must be very old" because of this. Furthermore, as his stats are immeasurable, there's a possibility that he is too incredible for human comprehension (according to Death Note 13: How to Read).
One of the eye-catch rules given in the series states that extra Death Notes found by Shinigami are generally expected to be returned to the Shinigami King, though this is clearly a rule that Shinigami are not forced to obey. Likewise, lost notebooks must also be reported to the King. Very little information is given about the character itself, aside from Rem's assertion that the King is not easily tricked, an achievement which Ryuk accomplished successfully. On the other hand, he is quite easily bribed, as Midora was able to trade thirteen apples for a second Death Note. Ryuk once referred to him as "that old fart," implying that there are Shinigami who don't like him all that much despite his high status. On another occasion, however, Ryuk seemed worried about "the old man back home" being mad at him and Rem when he, under Light's orders, wrote fake rules in the back cover of Light's Death Note. This hints that while Ryuk may not like him, he does fear him.
The Shinigami King doesn't seem particularly close or understanding of Ryuk as he stated that he couldn't picture Ryuk dropping his Death Note in the Human World as he considered it "boring," nor did he understand why Ryuk would be carrying two Death Notes.
The Shinigami King also seems to dislike, if not outright hate, any human who profits from using Death Note without actually writing in it. This is proven by how he let Light Yagami's campaign as Kira go on in the main series but killed Minoru Tanaka by using a new rule he made in the Never Complete One-shot manga. In the main series, the Shinigami King never appeared nor got in the way of Light's plans, presumably because he used a Death Note the way it was intended. In the one-shot chapter, however, as soon as he learns that Minoru plans to sell the Death Note without actually ever writing in it, he gets furious and writes up the new rule which kills anyone who either sells or buys the Death Note after using it. This ends up killing Minoru, rendering his plan moot despite it actually succeeding.
Though he is only referred to in the third-person and is never seen in the main series, the Shinigami King rules and governs all Shinigami. He also controls all "distribution" of each and every Death Note given to all Shinigami upon their "creation." It is unknown from the manga whether or not he creates Death Notes or just has a certain supply of them, as he is unwilling to replace lost ones. It is also not known whether the Shinigami King actually enforces all the various rules of the Shinigami Realm.
In other media
In Death Note: Light Up the NEW World, the King of Death, delighted by Kira's actions in the human realm, ordered the other Shinigami to find a successor.
Takeshi Obata once stated that he felt too afraid to design the Shinigami King; he said that he did, however, consider placing the Shinigami King on the book spine for Volume 12. He decided against it, as he felt that the spine would not have enough space to depict him.
- The last volume (volume 13) of the limited-edition anime DVDs included a figurine of the Shinigami King, but this currently only applies to the Japanese version, and volume 9 of the Australian DVD release.