|Leader|| King Cobra|
Madame Hydra (formerly)
The Serpent Society is a team of supervillains with various snake-like powers and abilities.
They later resurfaced when they took few civilians hostage in an underground railway which got the Avengers' attention to fight them.
Before the fighting, King Cobra had claimed to the Avengers that Madame Viper had sent them a message of support, which actually was Ultron's ruse to distract the Avengers while upgrading his programming.
When the fighting broke out, the Avengers nearly had them until Hank got in their way, trying to negotiate with them and end this peacefully which it failed. Hank's pacifist actions had let the Serpent Society to escape.