Rojo

Joey is the leader of a heavily armed female biker gang. When she tries to rob an armored truck, she is thwarted by Ben as Fourarms and two of Vilgax's drones coming after Ben. The remnants of one of Vilgax's defeated drones fuses with Joey as she investigates it, and she becomes Rojo (a combination of robot and her name), a powerful cyborg. The upgrade gives her the ability to fly, superhuman strength, invulnerability, metallic claws, and a pair of blasters attached to each shoulder. Vilgax is able to communicate with her through the parts and force her to track down the Omnitrix for him. Joey is turned back to normal when Upgrade shorts out the spare parts, after which Gwen knocks her unconscious for attempting a sneak attack on Upgrade.

Joey is greedy, wild and amoral, and not hesitant to attack innocent bystanders just because they annoy her. Neither her real name or her cyborg name is mentioned in the show, except for in "Ben 10 vs. The Negative 10," but are listed as such in the credits. Joey first appears in the episode The Alliance. She returns in Ben 10 vs. the Negative 10 as part of the Negative 10, with alien tech and armor presumably supplied by the Forever Knights. In that episode she is also shown to have a rivalry with Charmcaster over being the "baddest girl" in the group. In the battle, She interferes with Gwen and Charmcaster's duel but kicked away by Charmcaster and Gwen's combined spell power. Later she is quarrel with other Negative Ten members and later was trapped in the force field where Sub-energy once resides. It is unknown if she had escaped.