Light Yagami
Throughout the series, he observes and spies on the activities of the series' protagonist, Light Yagami, a high school genius. L attempts to expose Light as the infamous serial killer "Kira", who is responsible for massacring high-profile criminals worldwide through apparently supernatural means. As the series progresses, the psychological mind-game of cat and mouse between L and Light intensifies, and each becomes bent on uncovering the other's true identity through a series of intricate ploys and schemes. He serves as an ideological and visual foil to Light.