Ryuk

For a death god, Ryuk cuts a roughly human silhouette, though every detail is exaggerated into something unsettling. He stands very tall and gaunt, his skin a grayish tone tinged with blue and his mouth lined with pointed teeth beneath thin lips. Spiked black hair tops a face dominated by huge round eyes, their yellow whites set against vivid red centers. Rings crowd his unnaturally long fingers, and folded against his back are feathered wings he can extend whenever he wants to take flight.

What sets Ryuk apart from his fellow death gods is his refusal to simply idle away eternity, and the jeers other shinigami throw at that restlessness roll right off him. He latches onto Light precisely because the boy keeps surprising him, prying open rules and uncovering tricks in the notebook that even Ryuk had never known existed. That fascination never curdles into loyalty. He stays neutral about whether Light survives, lends help only when something is in it for him, and cheerfully sits on information his companion could use. Everything he does traces back to a hunger for amusement, since he finds the spectacle of a human wielding the notebook genuinely diverting. Clever as he is, he proves easy for Light to read and steer, his wants being so transparent. His most famous quirk is a near-addiction to apples, which he likens to the way humans lean on tobacco or drink; the shriveled fruit of his own realm tastes like sand to him, and a long stretch without the human variety leaves him contorting into knots and flipping into handstands. He also turns bashful around women and harbors a soft spot for video games.

As a shinigami, Ryuk owns a Death Note and prolongs his own existence by writing human names into it, the unused lifespans of his victims folding into his own. Anyone who has not touched his notebook cannot see him, he passes through solid walls, and his wings carry him after Light wherever the boy goes. The eyes shared by his kind let him read both the name and the remaining lifespan hovering above any person, the very power he can offer a human in trade for half their years. Before sending the book downward, he inks its instructions inside the cover in English, guessing that to be the world's most widely spoken language.

From the outset Ryuk warns Light that their arrangement carries one fixed clause: when Light's time runs out, it falls to Ryuk to record his name. The manga makes good on this during the final standoff, after Matsuda's gunfire leaves Light bleeding and pleading for the investigators' names to be written down. Ryuk lifts his pen as if to oblige, then reveals that the only name he set down was Light's own, judging that a man reduced to begging a death god has nothing left worth watching. The anime stages the same ending differently: Light slips out of the warehouse amid the confusion of Mikami's suicide, but his wounds doom him, and Ryuk, unwilling to loiter through a prison term waiting on the inevitable, writes the name himself with the parting remark that it has all been interesting. Light collapses beneath a vision of L, and Ryuk drifts back to the realm he had abandoned.