Zatanna Zatara was born in Gotham City, the unlikely result of a union between Giovanni "John" Zatara, a famous stage magician and illusionist, and the mysterious Sindella, a descendant of Atlantean stock and a member of the Homo Magi race. Sindella supposedly died in childbirth, though the whereabouts of her body are unclear.
Daddy's little girl, Zatanna helped in her father's act from a very young age, and quickly began to pick up the art herself. When she was a teenager, a man calling himself John Smith came to John Zatara for guidance and training in escape artistry. Zatanna and Smith were fast friends, but after his training was complete they did not see each other for many years.
John Zatara died from an unexpected brain aneurysm when Zatanna was twenty years old. Devastated with grief, she took over his act and began to make a name for herself in the field of stage illusion and escape artistry. Around this time, she was rescued by Batman when a criminal skeptic attempted to frame her. It didn't take long for her to realize that Batman was really John Smith, the companion of her youth, and that Batman/John was also wealthy playboy Bruce Wayne.
About a year later, Zatanna's Homo Magi heritage suddenly kicked in, and she found herself capable of real magic. Using her father's occult library, she managed to begin training herself in these newfound abilities. It was a great help when she discovered Shadowcrest, an abandoned extradimensional manor left to her by her father, where she quickly set up shop.
Zatanna would call on her old friend Batman when the Justice League began expanding its membership. He had utilized her mystical expertise on behalf of the League when Wonder Woman was transformed into a pig by the wicked witch Circe, and through discussion with Batman she secured membership in the group. Now, Zatanna works to get a handle on her new powers, to live up to her father's legacy as an illusionist, and to prove to herself that she has what it takes to be a hero.
Zatanna Zatara is a mess of dualities. She's an immensely powerful sorceress who is quite pleased with her vast power, while at the same time she wakes up screaming sometimes after nightmares of that same power going horribly awry. She's a beautiful, mysterious dame with legs like heaven and a penchant for idle flirting, but for all her extroverted behavior she never seems to really get close to anyone she meets. She's a good listener with all the patience in the world, and yet has no time to spare in mastering and expanding her eldritch powers.
Really, though, the most important contrast to be made within Zatanna's mind is the split between the overconfident, superheroic enchantress and the terrified young woman inside, insecure about her new place in life and unconvinced that she's got what it takes to play in the big leagues with Superman and Wonder Woman. Her confidantes are few, but they are treasured. Only Batman really knows that she's not quite as self-assured as she seems, and even he doesn't know much beyond the surface.
The enormously influential figure of her late father still looms large in her mind, even after years have passed since his death. Zatanna feels as though it is her duty and her calling to assume her rightful place as one of the earth's most powerful magicians. She's just not sure she's strong enough to do it.