Source: fandom.wikia.com
7. Jason Todd
(Batman, DC Comics)
Look, Todd is an obvious pick for this list, but that doesn't mean I can exclude him.
Todd was the second kid to take up the identity of Robin. He was a red-headed circus acrobat whose parents were killed by Killer Croc, and"”oh wait, that was all before Crisis on Infinite Earths retconned everything. Post-Crisis, Jason was a street urchin jerkheel who tried to steal the tires off the Batmobile. Batman took him in, but Jason was too tough-hearted and violent. He even threw a guy off a roof to his death. In A Death In The Family, The Joker broke out of Arkham, stole a nuclear bomb, and decided to sell it to terrorists.
Yeah, in case you haven't read it, THAT’S HOW THE STORY OF JASON TODD'S DEATH STARTED. That thing was bananas. The Joker was designated as the Iranian ambassador in that story. Like I said, bananas.
The Joker wound up getting Jason and his mom chained up in a warehouse, where he beat Jason with a crowbar until he's near death. He then left them both locked up with a time bomb. Jason threw himself on the bomb to save his mother, but failed, and they both died. Of course, Jason later came back, but his death still echoes as a meaningful comic book that everyone forgets is just insane.

