Watari

Gray eyes and a head of white hair give Watari the bearing of a distinguished elder. While operating covertly as L's aide, he shrouds himself in a long dark overcoat and a brimmed hat that conceals his features. Once he steps into the open before the Task Force, he trades the disguise for a black tuxedo finished with a hat and spectacles.

A celebrated inventor, Watari poured the wealth from his creations into founding Wammy's House, a Winchester orphanage that cultivates exceptionally gifted children and releases them into the world. For much of the story he stands as the sole person to have laid eyes on L and the only one able to contact the detective directly, signing himself onscreen with an ornate Cloister Black letter W much as L uses his own initial. To L he has been a father figure since the boy's orphanage days, even as he outwardly plays the dutiful butler. He is also schooled in espionage and a capable marksman. Lighter notes round him out: a fondness for Earl Grey and a distaste for untidy rooms.

Watari surfaces first at an emergency Interpol gathering, where he announces that L has taken on the Kira investigation, and throughout the early police meetings he acts as the buffer between the officers and the hidden detective. As the Task Force shrinks to its committed core and finally meets L face to face, Watari appears undisguised in his tuxedo and distributes the forged badges and belt buckles L has prepared. When L recruits Light Yagami, he instructs Watari to stay off the floor and communicate only through the laptop, reinforcing the illusion that more than one L might exist, a ploy the anime drops in favor of Watari endlessly bringing L sweets.

During the Yotsuba phase he saves Matsuda by shooting the pistol out of Higuchi's hand before the cornered man can take himself hostage. His end comes through Light's scheming: having maneuvered Rem into killing L, Light does not anticipate that the shinigami, desperate to protect Misa, will strike Watari down as well. As the fatal heart attack takes him, Watari triggers a kill switch that wipes every file at headquarters, exactly the failsafe L had told him to use should anything unusual befall him. Adaptations across the films, novels, and live-action dramas reshape his fate, in some cases sparing him entirely.