Anaconda is a criminal and a villainess from Marvel Comics.
A steelworker, Blanche Sitznski was selected by executives in the Roxxon Oil Company to be a special agent in covert operations. At the Mutagenics Laboratory of Roxxon's subsidiary, the Brand Corporation, Sitznski was bioengineered to have various permanent serpentine adaptations. Her first mission, as part of the new Serpent Squad, was to retrieve the ancient power object called the Serpent Crown for Roxxon president, Hugh Jones.
She was then invited to join the Serpent Society by Sidewinder and had to have an initiation test to steal some apparatus from the Brand Corporation. Constrictor the only invited snake-themed villain who had refused to join the society, tipped off the Avengers and Captain America turned up, who fought and defeated Anaconda. Later she was freed by Sidewinder and defeated the Constrictor for what he did.
Anaconda proved to be a mainstay of the Society, though when the terrorist Viper took over the Society, Anaconda was disloyal to Sidewinder and threw her support behind the new leader, and became romantically involved with one of the Viper's new members of the group, Puff Adder. When her teammate Diamondback, who had remained loyal to the Society, stormed their headquarters the Serpent Citadel with Captain America and his allies Nomad, the Falcon, and Demolition-Man, Anaconda battled Diamonback and Demolition Man.
Anaconda subsequently became a member of Superia's all-woman team of villains, the Femizons. While on the cruise ship Superia was using as a base of operations, Anaconda had a difference of opinion with the villainess Quicksand that turned to violence. Anaconda's constriction powers were little use against Quicksand's ability to turn to sand, however, and Anaconda lost the fight.
Anaconda later had a stint in Six Pack before rejoining the Serpent Society during the Civil War.
Anaconda appeared in The Avengers: Earth's Mightiest Heroes episodes "Ultron-5", "Along Came a Spider...", and "Yellowjacket", voiced by Vanessa Marshall. She is a member of the Serpent Society.