A

"The first child, A, was unable to handle the pressure of living up to L and took his own life, and the second child, Beyond Birthday, was brilliant and deviant."

- Mello (Death Note: Another Note, p 105)

Character
A was an original potential successor of L and a former resident of Wammy's House.

A committed suicide when the pressure of having to succeed L became too much for to handle.

Trivia

 * A is a mentioned-only character from Death Note: Another Note.