Riddler

History
The Riddler's compulsion stems from parental abuse that he endured as a child. After Edward got high scores on some important tests in school, his father, unable to grasp the fact that his son was brilliant and believing he had cheated, beat him out of envy. This, in theory, left him with a strong internal desire to tell the truth, and prove his innocence. This desire manifests itself in the form of his obsession with riddles. His madness, as well as his descent into crime in general, may also have roots in a yearning to rise above the anonymity that he possessed in his youth.

As Edward Nashton grew older, he opened a crooked carnival booth involving a diabolical puzzle. The customers would compete to solve the puzzle for prize money, but if they failed to do so, they would have to pay Nashton a small fee for competing. In every case, Edward rigged the puzzle in advance to ensure that the customer would always fail.

Unsatisfied with the small pickings of the puzzle booth, Nashton closed the carnival attraction and a confident Edward announced to himself he was clever enough to use his wits for crime and baffle the upholders of the law.

Nashton concluded he would commit puzzling crimes and always fix the duel of wits between him and the law so he would always win. Donning a green costume covered with question marks, he turned to crime and set out to achieve infamy as the Riddler. At first, the Riddler proves intially successful, launching a crime wave across Gotham City. Batman soon deduced that the new villain was leaving baffling clues for the law in advance of each crime and began acting on the clues to thwart the Riddler's puzzling crimes, although Nashton swifly evades capture again and again.

The Riddler's last riddle clue asks, "Why is corn so hard to escape from?" Batman concludes that the answer is included in the fact corn is also known as maize, which sounds like "maze" when pronounced. At the scene of his next crime, Nashton fled into a complex maze he had designed to be the ultimate death-trap and challenged Batman, who had entered the maze in pursuit, to escape from the labyrinth before a bomb, hidden in one of the many passageways, goes off. Batman escaped, but the explosion knocked the Riddler off a pier and sent him plummeting to his supposed doom.

But by the time two months had passed, the Riddler made it clear he has indeed survived his fall and resumed his crime wave, robbing cash prizes from a nationwide puzzle contest.

The Prince of Puzzlers was finally apprehended when he gave the citizens of Gotham City a charade clue which he anticipates will draw huge crowds to the Gotham Museum, where Nashton planned to steal some Egyptian artifacts and escape in the crowd. However, he is thwarted when Batman and Robin arrive and capture him before he can make his getaway. After being paroled from prison, the Riddler returns, and wishing for all of Batman's attention, helps the Dark Knight solve his latest case and apprehend criminals he has been preoccupied with chasing. Now with Batman's full time and attention, the Riddler sents him a puzzling riddle, which convinces Batman that the criminal is out to rob a flawless black pearl from a Gotham millionaire. Batman and Robin seize the Riddler with the pearl, only to learn he has lawfully purchased it with his own money. Later arresting the Riddler as he flees an art gallery with a priceless relic, Batman is shocked to learn the villain has lawfully inherited it from his uncle.

Shortly after, Batman and Robin figure out the Riddler has given them another puzzle-clue in the form of their two most recent encounters. The first scene of the first encounter being at the millionaire's yacht, the second at the Peale art gallery. Batman discovers there are actually two clues, one set to mislead him and the other reveals the Riddler's real crime. Batman decides that one of the clues is too easily unraveled and must be a false lead. Thus, the other clue must predict the scene of the Riddler's next crime. Solving the latest riddle, Batman rushes to the scene of the crime and catches the Riddler red-handed in the middle of a robbery, easily apprehending him.

The Riddler later appeared in The Question, being convinced to become a "big-time villain" by a prostitute met on a bus. He hijacked it and began asking riddles, killing and robbing anyone that got them wrong. The Question quickly subdues him by asking him philosophical riddles in return. He is outwitted and has a nervous breakdown before being set free as a reward for getting one last riddle right.

In the one-shot "Riddler and the Riddle Factory", the Riddler becomes the host of an underground gameshow that focuses on digging up dirt on celebrities. Many of the famous people that he humiliates end up committing suicide shortly afterwards, suggesting that perhaps the Riddler did more than just inspire their deaths. In the end, his actions turn out to be a front for his attempts to find the hidden treasures of "Scarface" Scarelli, a Gotham City gangster who lived long before Batman's reign of crimefighting.

Riddler had a working relationship with The Cluemaster, although he initially resented the villain for seemingly copying his modus operandi. In their first encounter, he set his fellow rogue up with a bomb and sent Batman off chasing riddles that would lead to its defusal, as well as away from his real plan: to steal a vast amount of priceless baseball merchandise. The two teamed up on a few occasions afterwards, and were working together on a big scheme shortly before Cluemaster's apparent death in the pages of The Suicide Squad.

He seems to be more rational and cautious than his fellow rogues. During the Batman crossover storyline No Man's Land, after Gotham City is ravaged by an earthquake and Arkham Asylum frees its inmates, Riddler elects to flee Gotham rather than stay behind in the lawless chaos that ensues.

It is during this period that he makes the poor choice of attacking Black Canary and Green Arrow in Star City, where he is easily defeated.