The Riddler is one of Batman's most iconic and intelligent enemies. Edward Nygma (or Nashton depending on the continuity) was always a smart individual, but his intelligence wasn't fostered by his abusive father or school bullies. Eventually, Edward became fixated on puzzles and riddles to a fanatical degree. This, mixed with his sense of victimhood, led Edward to become the Riddler and attempt many takeovers of Gotham City.
The Riddler first appeared in Detective Comics #140 by Bill Finger and Dick Sprang in 1948. Over the years, he became one of Batman's deadliest and most determined enemies, and he's left a notable trail of destruction in his wake.
10 Partaking In A Gun-Running Operation In Gotham Harbor
One of the more run-of-the-mill yet thoroughly destructive criminal operations that the Riddler has enacted is the gun-smuggling operation that he helped set up with a man by the name of Jake Hammer. It was set up out of Gotham Harbor. Admittedly, he was actually selling guns out of Gotham, but it was still a significant blight upon the city.
As the story usually goes, Batman and Robin were able to locate the Riddler and Jake Hammer, and they put both men out of business and into a jail cell.
9 Involving Random Innocents In His Criminal Escapades To Frustrate Batman
During one of the Riddler's earliest outings, Edward began offering cash prizes to any Gotham City citizen who'd come out to the scene of one of his crimes. The intent of this was to frustrate Batman and Robin by putting more bodies between them and the Riddler.
This not only slowed down the Dynamic Duo but also put these people in danger due to the nature of the Riddler's activities and the ensuing crush of people that showed up to earn some free money. This was particularly cruel for several reasons, and it shows how cold the Riddler can really be.
8 Feeding The Batman's Secret Identity To Hush
Hush, aka surgeon Tommy Elliot, is one of the most elusive and deadly villains to ever target Batman. Tommy was a childhood friend of Bruce Wayne who had his parents killed so he could get his inheritance early. However, Dr. Thomas Wayne saved Tommy's dad, leading Tommy to develop a grudge against the Wayne Family.
The Riddler is the reason Hush knew that Bruce Wayne and Batman were one and the same. Hush's primary target was Batman, and the Riddler gave Hush his elaborate and destructive plan. Hush's schemes put a lot of Gothamites in danger in order to attract Batman. One of Hush's plays involved Killer Croc kidnapping a young boy (who was Bruce's age when Thomas and Martha were killed).
7 Partaking In An Attack On The GCPD During Infinite Crisis
During the chaos caused by Infinite Crisis (by Geoff Johns and George Perez), Gotham City all-but collapsed. The villains that plagued Gotham for so many years were running rampant and brought the city to its knees.
Eventually, many of the villains and criminals of Gotham decided to take a shot at the Gotham City Police Department. The Riddler was among their number. He also took a place in the Battle of Metropolis with the Secret Society of Super-Villains. It was here that the Riddler was knocked into a coma by the Shining Knight's mace.
6 Enabling Doctor Death To Go On His Macabre Killing Spree
Doctor Death, aka Karl Helfern, was a man who created a formula intended to allow spontaneous bone growth to prevent wounds. He used this formula on himself and his colleagues, and it killed everyone it was used upon except Karl himself.
It was later revealed that Doctor Death and his horrid experiments were prompted by Edward Nygma, the man who would one day become the Riddler. While the Riddler didn't do any of this personally, enabling the sick actions of Helfern is enough to put a large mark on the Riddler's record.
5 Helping The Joker During His "Death Of The Family" Scheme
The Riddler also aided the Joker during his Death of the Family (by Scott Snyder and Greg Capullo) scheme. The Joker dared the Riddler to break out of his own Arkham cell, and Edward was able to do so with ease. The Joker named the Riddler "the Strategist" in Gotham's court of crime.
The Riddler seemed to contribute very little to the Joker's play, but the actions of the Joker during this particular story were so abhorrent that anyone associated with it deserves some admonition.
4 Creating A Labyrinth Around Gotham City During "Dark Nights: Metal"
The Batman Who Laughs gave the Riddler a card that imbued Edward Nygma with newfound power. This was during the Dark Nights: Metal story by Scott Snyder and Greg Capullo. The Batman Who Laughs just had one task for the Riddler: keep the heroes out of Gotham City.
The Riddler fulfilled this by creating a giant labyrinth around the city that kept the Titans, Green Arrow, and the Suicide Squad preoccupied. However, the Riddler played to form by also hiding a solution inside the Labyrinth, and the heroes eventually found it.
3 Waging A War Against The Joker During Batman's Second Year
The War of Jokes and Riddles (by Tom King and Mikel Janin) was a story told during the second year of Batman's crime-fighting career. The Joker found himself unable to laugh, and the Riddler tried to cure him with a joint scheme. The Joker retaliated by shooting the Riddler, and this led to a drawn-out war between the two.
Virtually all of Gotham's underworld was recruited by either the Joker or the Riddler, and the skirmishes raged across the city. Dozens of innocents were killed in the crossfire, and Batman became so enraged that he almost stabbed the Riddler to death.
2 Kidnapping Children And Attempting To Sacrifice Batman To Barbatos
Dark Knight, Dark City is a story by Peter Milligan and Kieron Dwyer that finds Riddler fixated on an occult ritual performed centuries ago by a cabal that included Thomas Jefferson. This ritual was intended to summon a demon by the name of Barbatos (who would later make an appearance in Grant Morrison's Batman stories as well as Dark Nights: Metal).
To summon this demon, the Riddler re-enacted several rituals and put Batman on a wild goose chase. The Riddler kidnapped four infants for this purpose, and Batman narrowly managed to save them all before being the prime sacrifice for Barbatos. However, the demon himself intervened to save Batman, and the Riddler fled in terror.
1 Taking Over The City And Sending It Into Chaos In "Zero Year"
Perhaps the Riddler's greatest gambit was his takeover of Gotham City during the Batman: Zero Year story by Scott Snyder and Greg Capullo. The Riddler, with the help of Doctor Death, knocked out the power to Gotham City, isolated it from the outside world, and turned it into his own personal playground.
Gotham City was in the state for months, with wildlife and vegetation making its way back into the city. Ultimately, Batman, Lucius Fox, and Jim Gordon managed to coordinate a plan that brought Batman face-to-face with Edward Nygma. Batman brutally beat the Riddler but left him alive to be taken in by the authorities.