Vox was a female Batman Villain mentioned in Secret Files Batman Villains #1 in 1998. She never appeared in the book however, she was merely mentioned.
Vox's first actual appearance was in Batman: Arkham Asylum -Tales of Madness, which took place during Cataclysm. After the Earthquake, Vox was released from her cell in Arkham Asylum by Joker and Killer Croc and partook in a scary story competition with several other inmates; first prize was getting to kill a guard. During the competition it is revealed that Vox hears voices. Vox tells a story about a young girl named Lisa, presumably Vox as a child, who came from an abusive home and violently attacked her younger brother when the voices in her head told her to. When the competition is over, no winner is declared so each inmate claims a different part of the Guard, with Vox choosing the left leg. Jeremiah Arkham regains control of the asylum but Vox's fate is not detailed. She appears again in the three issue arc Waxman and the Clown; a lead in to the No Man's Land event that explained what happened to the Arkham inmates when Gotham City was abandoned. At the end of the story, Jeremiah Arkham released Vox and the other inmates hoping that they would drift into Gotham which he assumed had been abandoned. Vox, however, was not seen during the events of No Man's Land.