Curaré was a member of the Society of Assassins, and its best and deadliest killer.
Nobody remembers Curaré's real name, and nobody has seen her face (apart from Batman, who was horrified by it). But everybody knows she's deadly, and possessed an unending knowledge of killer tactics. She was an excellent martial artist, and was designed to kill. She possessed a scimitar that has an edge no thicker than a molecule. It could cut through anything and deflect gunfire.
In the Society of Assassins, the price of failure was death, and Curaré was the first to run afoul of that rule when she finally met her match in the form of Batman and Barbara Gordon. Both of them, working together, managed to capture Curaré and saved district attorney Sam Young from her lethal blade. Curaré managed to escape, but then had to face the fatal consequences of her failure when the Society went after her.
However, she managed to turn the tables on the Society of Assassins, hunting every one of them down and erasing their minds, before they had a chance to kill her. She eventually destroyed the entire Society one at a time, with Mutro Botha being the last, and can thus be inferred to be the best assassin left in the world. She was soon captured by Batman.
Curare (spelled without the accent) is also the name of a poisonous plant used by some South American native peoples to tip their arrows, and by medical doctors as a muscle relaxant. Interestingly, one of the symptoms of curare poisoning is blueish skin.
Curaré has no speaking lines, other than a few grunts.
The only person to see her face is Terry McGinnis when he fought her as Batman. He only saw her face for a split second however, before she kicked him in the face. She might possibly be bald. A concept art was produced by the animators showing her unmasked, however.
Curaré reappeared in the comic book Batman Beyond #9, "The Last of her Kind", having set up her own society of assassins.