Teen Titans owned by DC Comics and Cartoon Network.
Full Summary: Raven died because of an accident during a mission to stop Dr. Light. Robin was the one nearby Raven, when Dr. Light blasted a powerful light beam above Raven; causing the walls of the building collapsed on her. Robin overwhelmed with guilty for he wasn't fast enough to save Raven and blaming himself that he didn't deserve being a leader who supposedly to protect his teammates or precisely his family.
WARNING: Major character death.