They have no compunction about killing, even as they themselves are ready to die for their cause. To many, they are simply terrorists, religious fanatics out to rid the world of those who do not share their beliefs. Since September 11, 2001, al-Qaeda of Osama bin Laden had been the face of terrorism. But with Osama's death in 2011, the group declined in prominence as his successor, Ayman al Zawahiri, proved not to be as charismatic. Little did the rest of the world know that a bigger, badder threat was just over the horizon.