The Red Hood Gang was created by Batman: The Killing Joke writer Alan Moore, who expanded upon the story told in Detective Comics #168 featuring the man who would become the Joker as a master criminal known as the Red Hood.
Major Story Arcs
The Killing Joke
In Alan Moore's famed story, the Red Hood Gang approaches a struggling comedian who was a former employee of Ace Chemical. The gang wanted this man to pose as their leader, and guide them through his old workplace in order to rob the building next door. This man, financially struggling to keep himself, and pregnant wife afloat, reluctantly agreed to the job.
Prior to the robbery, the man's wife and unborn son died in a freak accident, which lead him to try and back out of the robbery, something the Red Hood Gang wouldn't stand for, as they would then threaten and force him to go through with the job.
Unfortunately, during the robbery, Gotham City's new vigilante protector, Batman would show up to stop the crime. In the chaos that followed Batman's arrival, the man posing as the Red Hood Gang's leader falls into a vat of chemicals, and when he emerges in the water outside, he finds himself to have bleached skin, green hair, and a hideous smile. This man would later go on to become the Joker, Batman's most dangerous foe.
In the New 52 DC continuity, Batman writer Scott Snyder revisited the Red Hood Gang during the New 52's one year anniversary Zero Month, where all the books would be numbed #0, and revisit the past of starring characters. Snyder's story showed a Bruce Wayne who had just recently returned Gotham, had not become Batman yet, but nevertheless had started his crime fighting career.
One of Bruce's early targets was the Red Hood Gang, which he managed to infiltrate undercover. Unfortunately for Bruce, the leader of the gang knew his group had been infiltrated and managed to weed out a disguised Bruce as the culprit.
Though the gang attempted to kill him, Bruce manages to escape into the sewers after the police show up to break up the robbery. The gang eventually follows him into the sewer system, but a prototype motorcycle hidden in the tunnels allows Bruce to escape. The gang is later seen outside of Bruce's apartment, scoping it out for their next hit.