L's successor

L's successor or L's Heir is the person to succeed L if anything should happen to him.

Overview
L is known to all as the world's greatest detective, and his opinion is highly valued by world government officials. His status allows him to mobilize law enforcement whenever he needs them.

L remains hidden and communicates with the outside world via computer. He uses an electronic voice synthesizer to cover his voice, and his real name and appearance are currently unknown by the public.

Due to the dangers that come with being a world renowned detective, L's life is assumed to be at risk. If anything should happen to L, L's successor will assume the position as the greatest detective in the world.

Becoming a Successor
Little is known about how one is chosen to be a successor, though it seems that L himself chooses. The child is assumed to be a resident at Wammy's House, an orphanage created by L's mentor, Quillish Wammy

Near and Mello
L has two successors, Near and Mello. It appears that they were chosen at a young age, with Near being thirteen and Mello close to fifteen when they were introduced in the story. Of the two children, only one was intended to gain the title of L, but because of L's death neither child was officially picked. After learning of L's death, Roger proposed to the two that they work together. Near agreed, but Mello found it impossible to work with Near and gave Near the position as L.

The Current L
As shown in the manga one-shot taking place three years after the main storyline, Near remains the current L and solves cases under the L name.

Novel
The novel, Death Note: Another Note greatly expands on information regarding L's successors. Within the novel, two other successors are introduced: B and A. These two are referred to as the "first generation" of successors, having been chosen before Near and Mello. The first successor, A was unable to cope with the pressure of having to succeed L, and committed suicide. The second, B became a serial killer and later dies of a mysterious heart attack while in prison, presumably by Light or another owner of a Death Note.