Ryuk is a bored Shinigami that drops a Death Note, a notebook that allows the user to kill anyone simply by knowing their name and face into the human world in order to have relief from his boredom. Indirectly the giver of the notebook which gives Light Yagami the power to pass righteous judgment on others and establish an image said to be godlike by his worshippers and outside observers of the modern world in the story, Ryuk is a Shinigami whose motivations involve the pursuit of entertainment and stimulation from the activities which take place in the Human Realm.

Ryuk has a fairly humanoid appearance. He is extremely slim and has light-gray skin, almost blue-ish in color, with spiky black hair; thin, blue-gray lips; and sharp, pointed teeth. His limbs are abnormally long, and he wears rings on his fingers. He has large, round yellow eyes with bright red irises and retractable feather-like wings on his back that enable him to fly.

Ryuk regards Light as "interesting," specifically due to his experiments and the loopholes he discovers regarding the Death Note's rules and instructions, occasionally discovering abilities of the notebook even Ryuk did not know existed. Though he finds Light interesting, he does not care whether Light lives or dies and does not actively assist him as evidenced by his actions throughout the story. At times, he withholds important information from Light and only assists him when he has something to gain from it. As his only purpose in dropping the notebook was because he was bored, most of his actions are primarily motivated by wanting to see something interesting, as he sees Light's use of the Death Note and the way humans react to it as truly entertaining. Ryuk is intelligent, but Light's ability to understand his desires easily makes him able to be manipulated.

Knowledge: 7.5/10

Inquisitiveness: 10/10

Initiative: 9.5/10

Empathy: 5/10

Kills: 7/10