A female mercenary in service of the Ashram Monastery, an order to which Green Arrow once belonged. When Ashram's Exalted Master was killed by the renegade monk Lars, who intended to unravel the "Wisdom Key" that unlocked the powerful Book of Ages, Onyx sought Green Arrow's help to defeat the villain. In Ashram, Green Arrow and Onyx were defeated by the minions of Lars's, and the monk managed to take the Wisdom Key from Onyx. However, upon opening the Book of Ages, Lars was vaporized and left a skeleton. Later, Onyx appeared in Star City to battle a villain named Barricade. Barricade turned out to be Lars, who had been revived by his underlings. The spell which skeletized him was reversed only as long as he remained in contact with the Book of Ages, but with the Wisdom Key possessed by Onyx, he could make the reversal permanent. In a battle with Onyx, Green Arrow, and Black Canary, Barricade again met defeat and was reversed into a heap of bones.
Following this incident, Onyx was not to be seen for years. Recently, she briefly returned as part of Wonder Woman’s "task force" of super-heroines, battling the minions of Circe.