Alter Ego: Cassandra Cain
Occupation: Crime Fighter
Marital Status: Single
Known Relatives: David Cain (father), Sandra Wu-San (Lady Shiva) (mother), Mad Dog (adoptive brother)
Group Affiliations: Batman Family, Young Justice, Justice League Elite
Base of Operations: Gotham City
Height: 5ft 5in
Weight: 127lbs
Eyes: Green
Hair: Black
First Appearance: As Cassandra: Batman #567 (July 1999)
As Batgirl: Batman: Legends of the Dark Knight #120 (August 1999) Created By: Kelley Puckett, Damion Scott

A uniquely gifted warrior, Cassandra Cain was concieved and trained from birth with the intention of creating the perfect bodyguard for Ra's al Ghul. After many unsuccessful attempts to train children from birth in martial arts to make them inculcate it like a native language (the most successful being the abandoned child Mad Dog), David Cain, a member of al Ghul's League of Assassins, decided the right genes were necessary to create this "One Who Is All". Cain searched for the perfect mother for this child, finding her in the Wu-San sisters of Detroit, who practiced martial arts with each other nearly every moment of their childhood in a type of sister's language. Cain sympathized with the younger sister, Sandra, when he noticed that she held back out of love for Carolyn. To "help" Sandra reach her full potential, Cain murdered Carolyn, then lured Sandra into an ambush by the League of Assassins, where he defeated her. Cain spared Sandra from death on the condition that she bear his child, and leave her for him to raise. Awed by the potential heights she could reach in her physical talents now that Carolyn was gone, Sandra agreed to Cain's bargain in order that she might go on to become the unstoppable force of nature known as Lady Shiva: creator and destroyer. Shiva's hope for her child was that she might one day grow to be the one force that could stop her reign of destruction.

Trained by her father, assassin David Cain, to be the ultimate martial artist and assassin, Cassandra was not taught to speak. Instead, the parts of her brain normally used for speech were trained so she could read other people's movements and body language and predict, with uncanny accuracy, their next move. This ability lives up to her namesake; Cassandra in Greek mythology had the gift of seeing into the future, but was cursed so that nobody would ever believe her predictions. This closely relates to Cassandra's capability of 'seeing' her opponents' next move at the cost of being (initially) unable to speak. This also caused her brain to develop learning functions different than most, a form of dyslexia that hampers her ability to read and write.

When she was 8 years old, Cain took her to kill a businessman. After she did it, she "read" him as he died, she saw death as the man saw it. "Terror and then... nothing". In addition to scarring her emotionally, she realized murder, like Cain's profession, is wrong, and she ran away from her father (Batman eventually learned about this when Cain transmitted a video he had made of the murder to the Batcave, but Batman nevertheless continued to accept Cassandra after she allowed herself to get shot several times simply to protect an innocent man).

After spending the next ten years homeless, beating herself up mentally over what she'd done, she came to be one of Oracle's agents in the "No Man's Land" Gotham. After proving herself by saving Commissioner Gordon's life, she was given the Batgirl costume with the approval of both Batman and Barbara Gordon. She became Barbara's ward.

In 2000, Cassandra became the first Batgirl to get her own ongoing self-titled comic book series (the Barbara Gordon Batgirl having been featured in a couple of one-shot releases). A telepath "rewired" her brain to think with words (although speaking properly took longer), but at the cost of her ability to predict and read people. Unable to defend herself (although she could still perform the moves, she was now being caught permanently off-guard in combat due to her reliance on her ability to read moves), she stopped using the costume. Lady Shiva later taught her how to read people again - the cost being that, one year later, the two would fight to the death. Preferring to be "perfect for a year" rather than "mediocre for a lifetime", Cassandra accepted and Shiva retaught her in a night.

One year later, Cassandra kept the appointment - and died within minutes. Then Shiva restarted her heart, having realized that Cassandra wanted to die (although not why), and wanted a fight Cassandra would try to win. In the ensuing battle, Cassandra realized that Shiva had her own death wish, and defeated her, although she spared Shiva's life.

Batman regards Cassandra very highly. During War Games, he relied heavily on her to help control the violence of the gang war in Gotham City.

Following War Games, Batgirl moved to Blüdhaven with Tim Drake (the third Robin) at Batman's suggestion and with his financial support (Nightwing had been injured during the crisis, and the Gotham City Police Department had declared all costumed heroes illegal). There, Deathstroke took on a contract from the Penguin to kill Batgirl and decided to let his daughter Rose (the current Ravager) do the job instead. Cassandra beat Rose by critically wounding her and giving Deathstroke no choice but to get her medical attention.

Cassandra also went undercover in the Justice League Elite masquerading as an assassin named Kasumi. She revealed herself to Coldcast to tell him that he was not a bad person, right before he was accused of murder.

Cassandra gathered evidence that Shiva may be her mother and sought out Shiva to confirm this. After being proclaimed by Nyssa al Ghul as the "One Who Is All", the students of the League of Assassins split their allegiances, half following Shiva and the others Cassandra. In the ensuing confrontation, Cassandra was mortally wounded by Mad Dog (her "adoptive brother") while heroically saving one of the students under her leadership. Shiva revived Cassandra in the Lazarus Pit, then answered all of Cassandra's questions. Shiva (always having intended for Cassandra to free her from her life of killing) and Cassandra (convinced that Shiva could never be stopped from killing otherwise) fought "one last time". In an evenly matched battle, Cassandra managed to break Shiva's neck, paralyzing her. She attempted to place Shiva in the Lazarus Pit, but Shiva pleaded with her not to do so. In a seeming acquiescence to her wish, she impaled Shiva on a hook hanging over the pit, apparently killing her. The ending seems to suggest Cassandra has abandoned the identity of Batgirl and returned to her life as a wanderer.

One Year Later Cassandra took on the role of a villain by becoming the head of the League of Assassins. She has used her position as head of the League to draw in Tim Drake, the third Robin, as an ally. She began killing former students of her father, David Cain whom she deemed unworthy and used Robin to free David and reunite with him. She then urged Robin to kill David, and join her in leading the assassins, but when Robin refused, she shot her father herself. She and Tim then eventually engaged in a final battle where she maintained the upper hand. The fight came to an abrupt end, however, when an explosive device detonated, leading Cassandra and Robin to flee in different directions. Robin returned to find David missing, and all the ninjas' necks snapped.

She is also on the roster of the Titans East and is once again Batgirl. Cassandra remains in the role of a villain, under the command of Titans East's leader, Deathstroke. It is revealed that she is being drugged by Deathstroke.

Cassandra also recently battled Supergirl, in her role as leader of the League of Assassins. She is hired by an unknown figure to kill Supergirl, and attempts to do so by kidnapping Supergirl's boyfriend, Captain Boomerang. Supergirl arrives at the League's Tibetan headquarters to confront Cassandra, previously unaware of the kidnapping. Cassandra attacks Supergirl, wielding twin swords that emit red sun energy, which is harmful to Kryptonians. Just Cassandra prepares to deliver the killing blow, Kara mysteriously extrudes crystals from her body which wound Cassandra.