No Man's Land (1999)
Following a catastrophic earthquake (1998’s “Cataclysm” event), Gotham City was sanctioned as a "No Man's Land" by the U.S. Government and barricaded off from the rest of the country. In the chaos that followed, Gotham descended into a state of perpetual gang warfare and lawlessness. During this time, Bruce Wayne left the city in order to seek help for the city from the government, leaving the protection and organization of the city and its civilians to a small group of Super Heroes—one of whom was Huntress. She allied with Barbara Gordon, Nightwing and the newly introduced Cassandra Cain to stabilize the city.
During this time, Helena briefly took up the Batgirl mantle, calling herself "the Bat" and patrolling various territories before Batman ordered her to give it up. Helena resumed her Huntress identity and continued her work in Gotham, which culminated in a near-fatal encounter with The Joker.
Cry for Blood (2000)
Shortly after being accepted by Batman as a DC Super Hero allowed to operate within Gotham City, Helena was framed for the murder of a Mafia don who was shot and killed with crossbow arrows (BATMAN/HUNTRESS: CRY FOR BLOOD #1, 2000).
With his fragile trust in Helena shattered, Batman and his team moved to apprehend her as the killer, forcing her to team up with the eccentric hero the Question. Together, they proved her innocence while deducing the real murderer's identity and evading capture by Batman.
This story also reveals Helena's full origin, as it is intercut with flashbacks to her childhood, the murder of her parents and her training with relatives in Italy.
Birds of Prey (1999-2009)
Shortly after the events of NO MAN'S LAND, Helena was given a new costume and equipment by Batman, whose respect she’d slowly earned. With his support, Helena joined the Birds of Prey, a team run by Oracle, a.k.a. Barbara Gordon, former Batgirl.
Though Barbara and Helena did not initially get along, Helena formed a friendship with her teammate Dinah Lance, a.k.a. Black Canary. Despite that connection, the team dynamics remained strained, prompting Helena to quit and rejoin several times before becoming one of Oracle's most trusted teammates.
While working with the Birds, Helena became a member of the Outsiders (OUTSIDERS vol. 3 #8, 2004), but for only one mission.
Huntress: Year One (2008)
A retroactive look at Helena's earliest years as Huntress, this story explored her first real costumed outing in Gotham City, just before she turned 21. Here, Helena met Barbara Gordon, Batman and Catwoman for the first time. But, still consumed with rage and desire for vengeance, she maintained sole focus on her mission, at the expense of connecting with her fellow Super Heroes.
The New 52 (2011-2016)
Helena resurfaced in the New 52’s continuity as Matron, an operative of the international spy organization Spyral. Believed dead by the outside world, Helena took up a job teaching the next generation of super-spies at a boarding school in England, while simultaneously acting as partner to Dick Grayson (who’d infiltrated Spyral in the 2014-2016 series GRAYSON.)
Following DC UNIVERSE: REBIRTH #1 (2016), Helena severed her ties with Spyral and returned to Gotham to resume her life as Huntress. Most of her Mafia-based origin story was returned to continuity, which brought her into conflict with the Rebirth incarnation of the Birds of Prey, consisting of Barbara Gordon/Batgirl and Dinah Lance/Black Canary.
Despite their differences, Helena soon joined the Birds. She continues to operate with them today.