9. Nightwing's Death (Sort Of)
The highly anticipated follow-up to Trinity War, Forever Evil saw the Justice League battle it out with the Crime Syndicate from Earth-3, led by their Alfred Pennyworth. As the storyline proceeds, it is revealed that the bad guys held Nightwing as their prisoner.
The climax sees Batman together with Lex Luthor and others arrive at the Watchtower where the Syndicate had been camped. They find Dick placed in a Murder Machine, which in turn served as the trigger switch for a bomb. The only way to prevent it from detonating was if Grayson’s heart were to stop.
Despite Batman’s best efforts, Luthor is able to prevent the Dark Knight from saving his original protégé, leaving the once Boy Wonder to die in order to save to everyone else.
Now yes, this gets overturned eventually, as Lex himself revives Dick. But the emotional trauma, the impossibly high stakes nature of this moment still makes it intensely emotional still.