Evil Cindy is Cindy's evil clone and Evil Jimmy's girlfriend. She looks and sounds just like Good Cindy, but unlike Good Cindy, she's a complete monster like the other evil clones and she enjoys sadistically torturing people for pleasure. She lives on the Evil Earth. She hangs out with Evil Libby and Evil Brittany.
She only appears in the episode "The Trouble with Clones" where she is seen giving a presentation on the proper wedgie technique. Her instructions include reaching, grabbing, and pulling hard at a 90 degree angle, which she demonstrates on Evil Nick. She then proceeds to call Jimmy up to show a much more painful version of a wedgie involving jumper cables, which would deliver a high voltage shock. However, Jimmy revolts, tying her and Evil Libby up and subsequently electrocuting them. When Jimmy undoes the duplication process, Evil Jimmy breaks the dark matter chip to prevent the Evil Earth from vanishing and thus, she and the rest of Evil Earth are trapped in the Dark Matter Dimension.
Evil Cindy was going to return in season four, in which she and the other evil clones would escape from the Dark Matter Dimension and attack Jimmy and his classmates, who were on a field trip to an asteroid.