(Action Comics v1 001, 1938)
The Tigress was both Zatara’s first foe and his only real recurring villain, showing up a dozen times over 3 years. She acted in the role of what was occasionally called a “friendly enemy”: a villain of the opposite gender who the hero has a soft spot for, implicitly or explicitly because they’re horny for them. A Catwoman situation, in other words.
Like Catwoman and Batman, the Tigress occasionally teamed up with Zatara against a worse foe, and Zatara frequently let her escape at the end of a case out of horny sentimentality. Unlike Catwoman, the Tigress was absolutely a multiple murderer, running armed robbery, assassination and extortion rings at various times as well as acting as lieutenant for several other super-villains such as the Mad Lama.
Ultimately, Zatara caught the Tigress for the last time and seemingly persuaded her to reform. Whether it stuck or not, she never appeared in a comic book again.