Justice League: A Better World
During the events known as The New League of Shadows Lord Batman was approached by Talia al Ghul who told him in secret that that Ras al Ghul wanted him to be the Head of the League of Assassins and that the world needed the League and someone like Batman to stop the Justice Lords and specially Lord Superman if they got out of control. At the end Damian Wayne-Ghul son of Talia and Bruce was the one who killed Deathstroke and won the head of the League of Assassins disabling at the same time the League of Shadows.
[GM: Here I want to keep a list of important characters killed by the hero. If I forget some, please tell me.]
Super Dragon Soldier
Player: Jeremy Rios
DC HEROES RPG 3rd Edition p.161
DC Wikia entry