Emperor Joker (also known as Superman: Emperor Joker) was a nine-part DC comics storyline that ran in late 2000. It encompassed four Superman titles (Action Comics, The Adventures of Superman (known as Superman: Volume One before 1987 and after April 2006), Superman: The Man of Steel, and Superman: Volume Two.
The story features Superman finding himself trapped in a topsy-turvy world, where the Justice League of America have become villainous mockeries of themselves (he himself being a criminal), while the "real" Justice League is made up of various supervillains, and led by Bizarro. As Superman continues to try to make sense out of such a nonsensical, insane world, he slowly comes to the realization that it was not always like this.
Eventually, the fifth-dimensional imp Mr. Mxyzptlk informs Superman that Joker had stolen ninety-nine percent of his power, and had used it to recreate the universe to suit his whims. With the advice of The Spectre, Superman finds himself leading an assault against the all-powerful Harlequin of Hate, as The Joker's very insanity, combined with his reality-warping powers, is slowly tearing the universe apart - something that Joker is only too happy to condone.
Note: The first four parts of the storyline were given under the banner of "Superman: Arkham"; it was not until the end of the fourth part that Joker was revealed to be behind the altered universe.
Part 1: "It's A Mad, Mad, Mad World!"Edit
Originally presented in Superman (Volume Two) #160
As soon as the story begins, it is clear that something is very wrong: Superman is in a black-and-silver costume, and locked up inside Arkham Asylum (which is headed by Solomon Grundy and Calendar Man). In the first few pages, Superman bursts out of Arkham, and is soon confronted by the leader of the Justice League of America: Bizarro. Though aware of his status as a supervillain, Superman cannot help but feel that something is wrong; he is imprisoned for the murder of Lex Luthor, but neither he (nor anyone else, according to him) have heard of the man.
As the battle between Bizarro and Superman continues, more and more oddities of the strange new universe are revealed: Lois Lane has now taken Lex Luthor's place as a bald-but-brilliant scientist, and is the CEO of "LaneCorp". Jimmy Olsen, meanwhile, has the moniker of "Gravedigger Lad", who manages Bizarro's "Graveyard of Solitude". Last but not least, Aquaman has become a grotesque fish-human hybrid dubbed "Fishface", who attacks both Superman and Bizarro for going into the water, stating that "If Aquaman cannot go into the water, then no one does!"
Eventually, Bizarro overcomes Superman, and brings him back to Arkham (it is hinted that such a routine happens every night between the two). As he leaves, however, a piercing scream is heard all over the city, which, according to Calendar Man, is heard every night. The story concludes with Lois (who had earlier scorned Superman as the "most hated criminal in Metropolis, and helped Bizarro capture him) pouring over a newspaper detailing Superman's capture with interest, while Superman, locked inside his cell once more, declares that he will be free.
Part 2: "Crazy About You"Edit
Originally presented in Adventures of Superman #582
The night after the events of the previous issue, several more plot threads are depicted: a distraught Mr. Mxyptlk desperate to find Superman, and Supergirl, now a nun at "The Temple of Beatific Amazingly Wonderful Divine Holiness, Etc., Etc., Etc., Yadda, Yadda, Yadda", receiving visions of Superman's torment.
Superman escapes from Arkham once again, and reflects upon his mental state: for as long as he could remember, he had been escaping from Arkham, and brought back by Bizarro. Now, however, he is not so sure that this is how things always were, but every time he begins to gain a foggy memory of how things once were, they dissolve. This particular night, however, Bizarro does not come to attack him; instead, Lois takes him in on her private aircraft, under the guise of helping him gain his freedom.
On the moon, the twisted earth's JLA - comprising of Poison Ivy as well as several other wholly new characters - make their appearance, and Bizarro briefly communicates with them before heading off to Earth once more with Scorch, a demon-like woman with powers over fire, to apprehend Superman. At Weisinger University in Metropolis (which has been reduced to twelve "students", as rationale is frowned upon in the new world), meanwhile, Jimmy Olsen is caught in a battle between "The Flab" (a villainous version of The Flash) and the "noble and heroic Turtle", and is bitten by the Turtle. As a result, he transforms into "The Giant Turtle Boy" - a deliberate homage to one of his many Silver Age personas.
Lois and Superman are easily tracked down by the two members of the JLA, and, much to Superman's surprise and confusion, Lois releases him and shares a kiss with him. As soon as he leaves Lois' ship, however, Superman is cornered by Bizarro and Scorch, and though he momentarily fights them off, he finds himself eaten by the mutated Jimmy Olsen.
Part 3: "No Axioms"Edit
Originally presented in Superman: The Man of Steel #104
Superman, now removed from the bowels of the mutated Jimmy Olsen and captured once more, finds himself onboard the S.S. Arkham, the "UFO of irrationality". He is greeted by Skizm, one of the members of the new JLA, who informs him that he has been brought there because his mind had began to take a "dangerous turn" toward the rational. After proving Skizm's words true by refusing to perform his daily "futile escape", Superman is thrown into a ward with his "fellow 2+2 offenders".
While in the cell, Superman comes across John Henry Irons (now named Hank Aaron Irons), AKA Steel, the only man besides him who remembers the "forbidden" mathematical formulas such as the mass-energy equivalence concept. Now convinced that there is more to the world than just nonsense, as they had previously believed, Superman and Steel break out of the UFO to seek the truth to the topsy-turvy world. Skizm is alerted of the breakout, and sends both Bizarro and Bounty (another member of the JLA) to apprehend the two.
Shortly after the escape, Steel gains his costume back, and together with Superman, are able to overpower both Bizarro and Bounty. Unknown to the two, their victory has lead to a disruption in "The Pattern", allowing Mxyzptlk (who has been subject to numerous grievous injuries throughout the last two issues) to regain his memory of what had happened. Mxyzptlk informs Superman and Steel that the disruption will not last long, but they will find all the answers they seek on the JLA's moon base. Shortly thereafter, Mxyzptlk is crushed by a falling ten thousand ton weight, leaving Superman and Steel to fend for themselves.
Luckily, Lois Lane comes in the nick of time, and throws the two onto the S.S. Arkham, telling them to "land some blows against the Empire". As Superman and Steel fight their way across the UFO, she muses to herself that she has a feeling the two are going to cause a massive, unimaginable revolution in the world - a shifted world where she wants to come out on top. Her thoughts are interrupted, however, as the same piercing scream heard the previous two nights rings across Metropolis.
Part 4: "Supermanamrepus"Edit
Originally presented in Action Comics #769
The story begins with a look at the "new" Superboy, now a stereotypical teenage fast food employee at a burger joint called "Superburgerboy". Suddenly, the entire restaurant finds itself caught in the crossfire of a fierce battle between escapees from Arkham Asylum (Poison Ivy, Bizarro, Skizm, etc.) and the JLA (Martian Manhunter, Wonder Woman, Catwoman, etc.). In the meantime, Superman and Steel are heading toward the JLA's headquarters on the hijacked S.S. Arkham, relieved that their breaking out of all its prisoners have left only two members of the JLA guarding it.
Inside the JLA's headquarters, the two encounter "Gorgeous Gilly" a hideous woman with the ability to seduce any who make eye contact with her, though with a bit of help from a recovered Mxyzptlk, Superman and Steel overcome her. While Steel remains behind to deal with Gilly, Superman continues through the Watchtower alone, and eventually finds himself attacked by an enormous armored being known as Ignition. Ignition beats the Man of Steel to a pulp, taunting him with cryptic remarks, until he makes mention of Lois. An enraged Superman, remembering more and more of his former life, punches Ignition out of the Watchtower, fully intending to kill him.
At the last moment, however, Superman regains control of himself, and realizes that killing is something that only Superman, "the most feared criminal on Earth", would do. Superman then rips open a door, and finds the real Mxyzptlk inside - the one who had appeared up to this point having been a mere astral projection. Mxyptlk returns Superman's lost memory to him, and reveals the one responsible for creating the insane earth is none other than "Emperor Joker".