Green Arrow single-handedly tracking Prometheus down to his interdimensional lair and instantly killing him with a single wooden arrow when Prometheus had been able to shrug off much more powerful attacks throughout the series.
Complete Monster: Prometheus started out as a Magnificent Bastard in his inaugural storyline written by Grant Morrison. He then went on to suffer from severe Villain Decay in most of his follow-up appearances... until now. In his grand return following a one-shot that used Final Crisis to retcon all of the non-Morrison/Villain Decay stories into being about an impostor, he unleashed a wave of chaos, carnage, and torture on the heroes of the DCU; along with slaughtering countless D-list superheroes, he killed Mikaal Tomas's lover and Congo Bill's pride, sewed Freddy Freeman's lips together to keep him from speaking his magic world, cruelly lobotomized genius IQ, mutilated Red Arrow, and murdered 90,000 people in Star City, including Red Arrow's young daughter; all because, as a boy, the police shot his criminal parents to death in front of him, prompting him to vow to avenge them by "annihilating the forces of justice".
Critical Dissonance: Despite all of the backlash, the series still received Eisner Award nominations, including one for Best Writing.
Memetic Mutation: An unfortunate font choice made the title look more like "Gay for Justice" at a passing glance. Naturally, this caught on fast.
As noted on the trivia page, while he did a fairly lackluster job overall, Lian Harper's death was not James Robinson's fault, although it's one of the first things people usually blame him for.
A fair number of fans, and even people who aren't comic book readers, have conceded that Robinson's statement at San Diego Comic Con 2010 that he was inspired to cut off Roy Harper's arm as a tribute to Iraq War veterans by creating a superhero with a prosthetic that's not cybernetic was in very bad taste, regardless of whether or not it was honesty, a bold-faced lie, or something his editors told him to say. He contradicted this statement in the introduction of Cry's trade paperback, claiming that the editors told him that they wanted to put Roy in this direction. He also made absolutely no mention of his explanation at Comic Con.