Zatanna Zatara is a character who appeared in the DC Animated Universe.
The daughter of the famous stage magician and escape artist Zatarra, Zatanna joined him on tour as his assistant when she was a teenager, and also became good friends with his student "John Smith" - who was, in fact, Bruce Wayne, who wanted to learn sleight of hand and escapology as part of his training to fight crime.
She is voiced by Lacey Chabert, who was also original voice of Meg Griffin in Family Guy (before being replaced by Mila Kunis), and also voiced Eliza Thornberry in The Wild Thornberrys, Aleu in Balto, and Vitani in The Lion King II: Simba's Pride.
Zatanna makes her debut in a Batman: The Animated Series episode. She is an illusionist with no apparent magic powers. She developed a close relationship with Bruce Wayne (using the alias John Smith) during the years in which Bruce was traveling the globe learning skills from Zatanna's father that later serves well as Batman; in particular, escape artistry. In the episode Zatanna, she visits Gotham City with her magic show, but finds herself being framed by criminal magic debunker Montague Kane. Batman helps Zatanna clear her name, and by the end of their confrontation with Kane, she realizes Batman is really "John Smith". At the end of the episode, the two promise to keep in touch, as dear friends.
In the Justice League Unlimited episode, This Little Piggy, she helps Batman search for Circe after the villainess turned Wonder Woman into a pig. Zatanna is apparently aware of Batman's true identity since her last appearance ("Bruce! I haven't seen you for so long...") and knows well enough to perceive the Dark Knight's romantic relationship with Wonder Woman. It's revealed that after her encounter with Batman that she somehow came across actual magic power, which she now uses to help people as a crimefighter and secretly uses them at the same time during her magic show tours for public entertainment.
Zatanna is a member of the Homo Magi race and is genetically gifted with great magical talent. She can cast an incredible number of spells, which she usually does by speaking backwards as a tribute to her father. However, the backward-speaking is not always necessary for her to cast spells. Speaking backwards is as easy for her as it is to speak forwards. Zatanna has shown great control of her magic ability, which extends to an ability to elemental sorcery.