Dark and intelligent? [i]Monster[/i] Is quite long (Something like 70 episodes) about a guy literally trying to wipe away all trace that he ever existed. [i]Higurashi[/i] is extremely dark but is more into the horror genre; since it's based mainly around insanity there isn't much in terms of analytics though. Finally, [i]Ergo Proxy[/i] would work as well. That's the best I can think of other than Death Note for that combination.