The League of Shadows is a criminal and terrorist organization, formerly led by Ra's Al Gul. The group focuses on extortion, manipulation, and power-broking. They were formerly based on Infinity Island. Through the leadership of Ra's, they also act on behalf of the Light and continued to do so after Deathstroke became their leader.
At some point a long time ago, the League of Shadows was founded by Ra's al Ghul.As part of their training, all agents are programmed with hypnotic failsafe commands, to allow Ra's to exert full control over his minions.
In 2008, several standard League of Shadows members escorted the frail scientists who would come to be Brain and Ultra-Humanite into the jungles of Bwunda where they would assume their present forms and experiment on several apes of Solovar's troop.
Robin, Kid Flash, and Aqualad interfered with the plan, and managed to distract the assassins for a short period. In the end, Hook and Black Spider were defeated and arrested, but Gonzalez was killed by a third assassin who was hiding outside, waiting for her to exit the Farano Enterprises building. Hook and Black Spider escaped custody.
Around July 25, the League of Shadows abducted Dr. Serling Roquette to create for them a weapon from nano-robotics. This weapon, called the Fog, would be capable of eating through matter, as well as downloading top-secret plans from computers.
After Roquette was rescued by Red Arrow, the League sent Cheshire to kill her in order to prevent her from developing a computer virus that could disable the Fog. They failed; the Fog was defeated.
The League of Shadows attempted to launch a diamond lens into orbit, which would focus the light from the sun into a deathray. The plot was personally oversaw by the Shadow's leader Ra's al Ghul. Batman and Robin were able to foil the plot and as a result Ra's was accidentally killed when he lunged at them.
Ra's was revived in a Lazarus Pit by Sensei, Ubu and Talia. Shortly after their master rose, Matthew Hagen also emerged from the pit after six months of imprisonment. After Sensei and Ra's defeated the mutated Shadow, Ra's had him shipped to Gotham City.
The League continued to provide muscle for the Brain's BwundanKobra-Venom operation. Miss Martian impersonated a Shadow guard to infiltrate the hut where the gorilla children were held hostage. Later, in the main hut, a number of Shadows answered the Brain's call for reinforcements. They were defeated by Kid Flash, Djuba and Malavar.
After being stopped from getting too close to Lex Luthor by Cheshire, Red Arrow decided the only way to infiltrate the Light was by infiltrating the League of Shadows. And for that, he had to convince Cheshire. He posed as a rogue freelancer, which seemed to convince Sensei.
Because their search for the artifact had no results at the dig site, Sportsmaster looked through an exhibition at the Museum of Natural History. He escaped with the artifact, evading his daughter's squad by holding visitors hostage.
The Shadows provided security and menial labor on another dig site, this time in Siberia. Superboy and his squad incapacitated those in the base camp and confronted Sportsmaster at the dig's ice drill. Sportsmaster and his ally, Icicle Jr., had to evacuate because of avalanche danger, leaving both the Olympia and Verhoyansk artifacts behind.
Dozens of League of Shadows assassins served as backup on a summit between the Light and the Reach. Ready to intervene at any time, they were called in when the Team attacked. But the Team had counted on this; a fair number of them had infiltrated the Shadows and disguised themselves as them. With their numbers dwindled, the assassins were quickly taken out by the Team.