Jimmy Olsen (JLA: The Nail)

In the DC Comics Elseworlds story "JLA: The Nail" it is revealed that that world's Jimmy Olsen was exposed to Kryptonian technology and given powers akin to those of Superman, but also driven mad. Descending into bitterness at his past failed attempts at heroism, Jimmy Olsen instead became a villain, conspiring behind the scenes to orchestrate various disasters designed to frame the superheroes and make the world think they were malevolent aliens in disguise.

History
The Jimmy Olsen of "JLA: The Nail" first appears as an assistant to Lex Luthor (here mayor of Metropolis). It is revealed that Jimmy Olsen repeatedly attempted to be a superhero but every one of his attempts was an embarrasing failure. Jimmy claims that now he is disillusioned with superheroes and no longer believes that they are what the world needs. His role for most of the story afterwards if fairly minor until near the end when Lois Lane confronts Lex Luthor, believing him to be the mastermind behind the crises that have been happening throughout the story. However, what she finds is Lex Luthor catatonic.

Jimmy Olsen then appears and reveals that he is the true mastermind behind everything that has transpired, and in fact possess Kryptonian powers. The reason for this is that years ago, Luthor discovered Kal-El's shuttle and sought to tap into it's secrets. Upon discovering trace samples of Kal-El's DNA, Luthor became obsessed with trying to find a way to graft the DNA onto himself and through that give himself the incredible powers manifested in the clones of Superman made.

Using Jimmy Olsen as a test-subject, Luthor got more than he bargained for when Jimmy became incredibly powerful, but also dangerously cunning and psychotic. Jimmy states that his plan is to rebuild Krypton on Earth, and that only those among humanity willing to serve him will survive. Knowing that the superheroes of Earth would stand in his way, Jimmy orchestrated the events earlier in the story that led to the public's growing distrust of them, including giving the Joker hi-tech gauntlets with which he caused a riot at Arkham Asylum and killed Robin and Batgirl, itself an act that prompted Batman to kill him on live television.

Now more unstable than ever, Jimmy attacks the Justice League, who have been freed from captivity by Batman, Batwoman, Flash, and Atom. Though the assembled heroes do their best to stop the madman, Jimmy is simply too powerful for them and defeats them one by one. The battle ultimately goes to the outskirts of an Amish farm where Jimmy attempts to beat Batman to death, demanding that Batman admit that he's a god. At that moment however, one of the Amish steps forward to stop him: Kal-El, here having been raised by an Amish couple instead of Jonathan and Martha Kent. Recognizing Kal-El as the occupant of the shuttle and the owner of the DNA that gave him his powers in the first place, Jimmy attempts to persuade Kal-El to join him, and then murders his foster parents in cold blood when they attempt to convince him to stay out of the rest of the world's affairs. Enraged by this callous act, Kal-El attacks Jimmy, leading to an apocalyptic struggle that only ends when Jimmy's body begins to violently reject his stolen Kryptonian DNA. Right before he dies, Jimmy ironically notes that he and Kal-El "should have been friends".

Personality and Traits
In contrast to mainstream Jimmy Olsen, who is typically shown to be good-natured and friendly, if not also laid-back and naive, the version seen in "JLA The Nail" only pretended to be this and in reality was a violent, psychotic, and vindictive individual whose exposure to Kal-El's DNA had driven him mad. Seeking to turn Earth into a new Krypton, Jimmy displayed clear megalomania when he noted that only the humans who would agree to serve him would live. He also showed a complete disregard for everyone else around him, manipulating others in various ways from behind the scenes and being totally indifferent to the chaos and destruction caused by his attempts to discredit the world's superheroes, who he had become contemptuous towards after so many failed attempts at heroism.

Jimmy was also shown to be sadistic and sociopathic, callously murdering an innocent couple after deciding that their attempts to urge their son to remain neutral and uninvolved were "tedious" and then casually brushes off his act as Kal-El reels from the deaths of his foster parents.

Finally, Jimmy had a clear god complex, yelling at Lois to take him seriously and also later demanding that Batman admit that he was a god. In all, the version of Jimmy Olsen seen here was utterly evil and completely bereft of redeeming qualities.