2. Swamp Thing
Scientist Alec Holland started off his day by researching secret plant growth formulas, and ended it by being murdered. Covered in burning chemicals, he fell into the swamp surrounding his lab, where the plant life re-animated him into a giant vegetable monster. Swamp Thing led a classic Frankenstein existence after that: wandering the land as an outcast, defending himself from man while trying to reclaim his own humanity. Pretty rough, right? It gets worse.
Shortly after writer Alan Moore, known for his lighthearted, cutesy-wutsey comic books where nothing bad ever happens, took over the title, our mossy hero was gunned down by the evil Sunderland Corporation. His body was frozen, dissected, and later revived only to discover the horrifying truth: he was never human at all.
Alec Holland died from his injuries. His decomposing body was consumed by swamp plants, which (thanks to the aforementioned chemicals) absorbed his memories and began to believe that they were Holland himself. Swamp Thing was never human at all, just a confused pile of peat moss with legs. That's a pretty heavy truth to lay on a man. Or, in this case, a seven-foot-tall chia pet.
For years, Wolverine's origin was shrouded in generic tough guy mystery. However, the 2001 limited series Origin finally revealed a very Batman-esque background for the moody hero: A boy of privilege, James Howlett witnessed a disgruntled servant-turned-burglar kill his father. The trauma caused young James to pop his claws for the first time and murder the burglar. Big deal, right? On the spectrum of vigilante-producing calamities, that's some MyFirstTragedy Playset stuff right there. But finding out that burglar was your mother's lover? And that he may have been your biological father? And then watching your mother blow her own head off with a shotgun in response to the whole debacle? Now we're talking. There's nothing like a little triple murder-suicide to put a foppish dandy on the road to ruthless berzerker killing machine.