When I think about suicide in literature I immediately think Dostoevsky.
SPOILER ALERT
Mainly I think of Smerdyakov and Svidrigalov. Which leads me to believe that the act of suicide is the most selfish act imaginable (at least in Smerdyakov's case).
But then I think of Romeo and Juliet.
And Othello.
Now I don't know what to think about suicide. But all of those characters provide good case studies.

