Ra's al Ghul
The League of Assassins is a cult-like organization of trained killers formerly led by Ra's al Ghul, an enemy of Batman. The League of Assassins was founded by Ra's al Ghul (exactly when is unknown) to be "the fang that protects the head" ("Batgirl" #67, 2005). Members of the League demonstrated willingness to die at a word from Ra's. They have included some of the most dangerous assassins in the world, including Lady Shiva, David Cain, and master archer Merlyn.