The Fiddler was originally an ordinary thief, Isaac Bowin, who was caught stealing from a merchant and imprisoned in India. In jail, he met an Indian fakir who taught him his hypnotic powers. The Fiddler constructed a crude violin whose music had magical properties, allowing him to hypnotize people or destroy objects. He then escaped from jail, killing both the fakir and the merchant who he had robbed.
The Fiddler plotted to blame his crimes on his twin brother, a famous violinist named Maestro Bowen, and take his place. He was defeated and exposed by the Flash and apparently committed suicide by throwing himself into a river. He survived and later attempted to break the Flash's confidence by staging robberies that would fail without the Flash's help, letting him think he wasn't needed. Once Garrick retired, the Fiddler began committing crimes without opposition. Joan Williams dressed as the Flash to stop him and Garrick also intervened, with the Fiddler apparently being killed by a train. He later resurfaced as a member of the first Injustice Society.
Years later, in "Flash of Two Worlds", the Fiddler escaped from jail with two more of the Flash's old enemies, Shade and Thinker. They found themselves opposed by not only Jay Garrick but also the Earth-One Flash, Barry Allen, who had accidentally crossed into Earth-Two. Having robbed an armoured car, the Fiddler hypnotized the two Flashes into stealing jewels for him but forgot to tell them they couldn't try to escape: They placed small gems in their ears to block the sound, then Allen manages to cuff the Fiddler before the Flashes took down the other two villains. By this time, the Fiddler was using a Fiddle Car shaped like a giant violin.
The Fiddler later found a way to use his music to breach the barrier with Earth-One. Allied with Wizard and Icicle, he contacted Earth-One villains and formed the Champions of Crime, committing crimes on each other's Earth in order to confuse the heroes. As a result, the Justice League and Justice Society had their first team-up to defeat the Crime Champions.
After the Earths were combined during "Crisis of Infinite Earths", the Fiddler remained an old enemy of Jay Garrick. During an encounter with Hawkman, the Fiddler learned the fakir he had learned from was actually a demon he had unknowingly entered into a faustian pact with and was dragged off to a hell dimension. He reappeared without explanation as part of an army led by the demon Neron (who possibly revived him). He later joined the Secret Six but his performance on their first mission was so poor that he was killed by Deadshot.
In Other Media
The Fiddler's only animated appearance is in an episode of Justice League Unlimited, where he has a silent cameo as one of the patrons of a villains' bar.
A female version of the Fiddler, Izzy Bowin, appeared in the Arrowverse during the fourth season of The Flash, portrayed by Miranda MacDougall. She gained her powers after the Flash accidentally caused her to be exposed to dark matter. The Flash and Elongated Man tried to convince her she needed to learn how to use her powers to protect herself, but she underestimated the threat of Thinker, who killed her and possessed her body.