- "My name is Nyssa al Ghul, and revenge is just the beginning of what I want."
- —Nyssa al Ghul[src]
Nyssa al Ghul, alias Theresa Walker, is the former Secretary of Homeland Security and the daughter of Ra's al Ghul, the legendary head of the League of Shadows. When Gotham became No Man’s Land, Nyssa went rogue and plotted to have all of the criminals in the city illegally killed. She also sabotaged any efforts made to help the citizens, resulting in the deaths of innocent civilians. After her activities were exposed, Nyssa went into Gotham to make sure her plans succeeded.
Nyssa saved a fatally wounded Eduardo Dorrance, and had Hugo Strange save his life, leading to the creation of Bane. She then revealed her true identity to Bruce Wayne and Barbara Kean, and tried to take her revenge on them for the part they played in her father’s death. After a battle with Jim and Barbara, which resulted in Barbara stabbing her, Nyssa retreated and left Gotham when her plan ultimately failed.
Nyssa al Ghul was born the daughter of Ra's al Ghul, the leader of the League of Shadows. For unknown reasons, Nyssa infiltrated the government under the alias of "Theresa Walker" and became the Secretary of Homeland Security. At some point, Nyssa visited the prison Peña Duro and met Eduardo Dorrance, she saved him from the prison and gave him a new purpose, to help her change the world.
After learning of her father Ra’s al Ghul’s death in Gotham at the hands of Bruce Wayne and Barbara Kean, an enraged Nyssa vowed to complete her father’s work by destroying Gotham and getting revenge against his killers. According to Eduardo, she had almost succeeded in convincing her superiors to wipe Gotham completely, stating that it was only filled with evil criminals until her actions were exposed.
No Man’s Land
Nyssa secretly orders Hugo Strange to implant mind control chips in Edward Nygma and Lee Thompkins when he revives them under the orders of Oswald Cobblepot, who wanted to save them. In addition, she had a mind control chip put in General Wade's brain and possibly several other people in order to succeed in completing her father's mission. As a result, the chips being activated in someone's head, lead to loss of memory as shown when Edward isn't able to remember his actions during the time that the chip was activated, however, it has been shown that the person is able to remember those events if their head is hit with enough force or shocked with enough electricity.
Beginning her mission
When Wayne Enterprises sends a chopper with supplies to Gotham City, Nyssa uses a mind-controlled Edward to shoot the chopper down with a rocket launcher. Later, she responds to one of Jim Gordon’s radio messages, saying she is a friend and wants him to know he has allies across the river. She promises that she would find a way to help the people stuck in Gotham, without telling him who she is.
Soon after, she tried to persuade her superiors into believing that Gotham was filled with criminals and was not savable by using Edward Nygma to destroy Haven, a community created by Jim Gordon for the innocents left in Gotham so that her superiors would see the destruction and madness within Gotham. In order to keep her actions a secret, Nyssa continues to talk with Jim as he tells her about the destruction of Haven, revealed to be caused by Edward Nygma. She expresses her sympathies and asks if he knows who is behind it. Jim states that they don’t know yet, and Theresa attempts to reassure him by telling him that she is working on getting him help. Jim snaps, telling her that she has been saying that for weeks. Nyssa tries to reassure Jim, but he turns off the radio in anger, cutting her off in mid sentence. 
Sending in the Delta ForceNyssa sends a Delta Force lead by her sub-ordinate, Eduardo Dorrance, in order to extract Hugo Strange from Gotham City, and kill Edward Nygma. After making sure that Edward was the prime suspect for the destruction of Haven, she orders Eduardo and his Delta Force to make sure he was dead so they were able to move foward with their mission. When Edward Nygma finally finds Hugo Strange, Eduardo and Jim succeed in finding Edward and Hugo where Eduardo finally reveals the truth by controlling Edward in front of Jim Gordon and trying to force Jim into killing Edward to prove his loyalty to him, which he doesn't do. After Edward is ordered to hunt down Jim Gordon and the Delta Force reveals their true purpose, they attempt to taking over the GCPD and locking anybody up if they aren't able to agree with Eduardo's actions. Under Nyssa's orders, the Delta Force continue to hunt down Jim Gordon and Edward Nygma, who was cured of the chip's mind-controlling capabilities with the help of Lucius Fox, where they find the two at The Sirens nightclub, leading to a fight.
When Eduardo and Jim get into a fist fight, a wounded Eduardo is found by Nyssa, who gives him a defibrillator mask to give him enough strength to live, telling him that he won't die yet since there is still so much for him to do in their mission. She also tells him that Hugo Strange will fix him soon before he says Jim's name, reassuring him by saying that they had a second operative, Lee Thompkins, who would kill him.
Getting revenge for her fatherSometime after, Nyssa brings Eduardo to Hugo Strange's lab, she reassures him by telling him that'd she keep the promise that she made in Peña Duro and give him a true purpose as well as the strength to see it through. As Hugo Strange is injecting a chemical into Eduardo, Nyssa tells him that he will be the "bane" of criminal elements and anyone who opposes their actions. Later, she orders Eduardo, now known as Bane, and his Delta Force to capture Jim Gordon and Bruce Wayne in order to bring them back to her, during the reunification deal. Once they were both captured and brought to an old mansion, Jim mentions that he knows that the name "Theresa Walker" is just a cover-up but doesn't know her true name which she claims that Bruce Wayne will help them figure it out. Nyssa claims that she's punishing Gotham for the sins of Bruce Wayne before giving Bane the heads up to torture Jim until Bruce is able to figure out who Nyssa is doing all her actions for. This continues until Bruce says Ra's Al Ghul's name and eventually figures out that "Theresa Walker" is actually his daughter, "Nyssa Al Ghul" before she states that revenge is just the beginning of what she wants. Since Nyssa knows that Barbara Kean had helped with the murder of her father, she orders Bane to capture her from the clinic, despite Barbara being pregnant. After Jim threatens to destroy everything Nyssa had, she tells him that she has nothing left except for her father's mission before telling Jim that Eduardo wants him to join their mission, however, he rejects the offer. Nyssa continues to taunt Bruce and when Bruce asks what Nyssa wants from him, she tells him that there's a military order known as "Special Order 386" and that when an event occurs causing Gotham to be permanantly lost, a contingancy plan was created to reduce the city to rubble, however, Bruce tries to stop her by telling her that there are still innocent people left in Gotham. Though, Nyssa doesn't seem to care for innocent lives since she states she only wants Bruce Wayne to suffer before he dies before walking away. After Bruce escapes and finds Jim Gordon and General Wade, he tells him that Alfred and the GCPD are on their way to the clinic that Barbara is at and that he doesn't know where Nyssa had went. The three of them try to stop Nyssa from using the military to wipe out Gotham before she mind-controls General Wade and Harvey find them, telling Jim that Barbara Kean, Lee Thompkins and her baby are safe. Using General Wade, she activates "Special Order 386" before Bruce, Harvey and Jim are taken away. When Lee and Barbara arrive at the Sirens nightclub, they find out that the employees of the bar have all been killed before Nyssa appears and knocks out Lee. She introduces herself to Barbara, telling her that she knew his father, frightening Barbara. When Bruce, Harvey and Jim escape General Wade's soldiers, they find out that Nyssa managed to intiate "Special Order 386" as they watch helicopters fly into Gotham and drop explosive bombs on the buildings in the city.
Capturing Barbara KeanWhile Gotham was under attack, Nyssa captured both Barbara and her baby daughter, bringing them both to City Hall. She begins to examine a knife as she sits next to Barbara's daughter and asks Barbara if she recognizes the knife which was used to kill Ra's al Ghul, however, Barbara threatens to make Nyssa meet the same fate as her father if she touches the baby. Nyssa responds by telling her that that it's cruel to let the baby get attached to Barbara when she won't around for much longer. Nyssa continues to taunt Barbara by telling her that her and Bruce Wayne will watch Jim Gordon's greenzone and the rest of Gotham be destroyed before she allows them die. Nyssa claimed that her father got his reputation by destroying empires and that it's now her turn to do the same. Then, Barbara told Nyssa that there was a submarine in the docks that is filled with gold for her and that all she had to do was leave the city and let Barbara and her baby go. However, Nyssa vowed to take Barbara and Jim's daughter and raise her to be an "al Ghul." Nyssa asks a mind-controlled General Wade if the army has landed and orders him to make them proceed with her plan. As a result, she managed to have Bane command the military and follow her orders. When Jim Gordon manages to get into City Hall and rescue Barbara, however, when they plan to save their baby, they are faced with Nyssa and more soldiers that force them to surrender. Nyssa taunts Gordon by telling him that he's finally seeing his baby and she wish she had a camera. When Gordon asks for the baby back, she says that she won't and that they should put down their guns or the baby will be hurt in the crossfire. Nyssa continues to taunt them by telling the two that the army is making their way to the greenzone while Bane hunts down Bruce Wayne. Nyssa claims that it's over and that her plan to burn Gotham will succeed and tells Barbara that she will be dealed with once Gotham is destroyed, forcing her to watch her hand-to-hand battle with Jim Gordon.
As Nyssa manages to get the upperhand and send Gordon onto the ground, she was getting reports that the Wayne Enterprises tower was destroyed in order to seperate Bane and the US military from Bruce and Selina. She asks if there's another way around the tower but ultimately orders them to blast through the tower. While Nyssa contacted the army, Gordon grabbed handcuffs off of the ground and hides them with him. After Nyssa is off the phone, Gordon tells her that their fight hasn't concluded and Nyssa replies by telling him that that the greenzone's destruction is only delayed and will still happen. When Nyssa is about to kill Jim Gordon, he handcuffs her to him and disarms her, continuing to fight her while Barbara kills the remaining soldiers in City Hall. Nyssa claims that others have tried to defeat her but failed and that Gordon won't succeed, managing to fight both Gordon and Barbara off alone. She claims that she has her father's blood and his training but Gordon asks if she ever stops talking before she finds herself stabbed by Barbara just as she and Bruce stabbed her father over a year ago and Barbara gloats to Nyssa on how they both like to be stabbed by the same weapon. As a result, she had General Wade kill himself so he would not repeal Special Order 386 before she escapes City Hall and locks the two in there, telling them that she'll enjoy watching Gotham's destruction and that her legacy will soon be completed.
After Bane's defeat, a wounded Nyssa is surprised that Barbara was telling the truth about the submarine and eventually retreats to the docks to take Penguin and Riddler's submarine filled with Penguin's loot and his dog, Edward, leaving Gotham for parts unknown after her plan to destroy Gotham and get revenge for her father failed. Her current whereabouts are unknown.
- "Nyssa al Ghul is still out there, and she and Bane were right, all of this happened because of me, because people were trying to hurt me and the people I care about."
- —Bruce Wayne to Selina Kyle[src]
Even after her depature from Gotham, Bruce is still threatened and unsettled by the fact that Nyssa is still out there and not in the custody of the GCPD. In addition, Bruce talks to Selina about Nyssa and Bane being right about all of the people trying to hurt him or the people he cared about and their attack on Gotham happening because of Bruce which leaves Bruce blaming himself for the damage brought upon Gotham.
As a result of Nyssa stealing the submarine on the docks filled with Penguin's loot and his dog, Riddler and Penguin are both infuriated and believe that she's probably somewhere on the mainland where she cannot be tracked. Furthermore, they claim that they have been left with nothing after all of their hard work and that they are now back to where they were at the beginning because of Nyssa.
At first, Nyssa seemed kind and sympathetic to Jim’s plight. However, she is really cold and calculating. She used Edward Nygma like a tool to destroy Haven, killing 300 people and shooting down a Wayne Enterprises relief chopper. These are acts that Nygma and many other criminals, despite having previously committed murder themselves, found deplorable. At the same time, Edward was a disposable pawn to her and she wanted Jim to kill him once he had outlived his usefulness to her.
She is consumed with revenge and utterly spiteful (possibly petty as well), as her agenda to destroy Gotham is not merely to carry on her father's work but also take revenge upon Bruce Wayne for killing her father. Her thirst for revenge extends to Barbara Kean for her equal complicity in the killing of Ra's. She seems to be a little cold-hearted when she orders Eduardo to hunt down Barbara, knowing that she is pregnant. She intends to make Bruce suffer by forcing him to watch as everything and everyone he cares about is destroyed before she kills him. Also, Nyssa shows some type of selfishness when she decided to leave Gotham without telling her subordinate, Bane, or the other Delta Force soldiers, proving she was just looking out for herself. Ultimately, she is much more a monster than her father; Nyssa has no qualms with murdering and harming others in unnecessarily drawn-out plans.
- The peak of human physical condition: As a member of the League of Shadows, Nyssa is in top physical condition. She was able to knock out Lee Thompkins with a single hit and was able to overpower Jim Gordon. She implements acrobatic moves into her fighting style. She survived being stabbed in the abdomen and was still able to escape.
- "You think you can defeat me? Better men and women have tried and failed."
- —Nyssa al Ghul to Jim Gordon
- Master hand-to-hand combatant/Martial artist: As Ra's al Ghul's daughter, Nyssa is a highly-skilled fighter. This seeen when she was implied to have singlehandedly taken down the female employees working in the Sirens Bar. She was also able to maintain the upper hand in her fight with Jim Gordon and Barbra Kean before she was maneuvered into being stabbed. Her fighting style seemed to be comprised of Karate, Taekwondo, Muay Thai, Jujitsu, Judo, and Krav Maga.
- Master knife wielder: Nyssa is very proficient in utilizing a knife in combat. This seen when she used the Kurdish dagger to slaughter all the female employees working in the Sirens Bar. She was also able to use the Kurdish dagger again during her fight with Jim and Barabra.
- Expert markswoman: Nyssa is highly trained with firearms. This is seen when she shot a thief from a few yards away.
- Master tactician/Manipulator: Nyssa is highly skilled in military strategy and tactics, as well as manipulating others. She was almost able to convince her superiors that Gotham was filled with criminal elements and was able to hide her plans and identity before she was exposed.
- Master leader: Nyssa was able to lead Eduardo Dorrance and Delta Force in the attack on Gotham.
- Infiltration: Nyssa has shown great skills at infiltration that she was able to get a job at the highest levels in the US government before she was exposed in her role in the Gotham City controversy.
- Stealth: As a member of the League of Shadows, Nyssa is highly trained in stealth, she was able to sneak up on Barabra and Leslie Tompkins at the Siren's bar.
- Indomitable will/High pain tolerance: She endured the pain of a stab wound in the abdomen and was still able to escape.
- Handgun: Nyssa used this hangun to kill a thief.
- Kurdish dagger: Nyssa is implied to have used the knife to kill the employees of the Sirens Bar. She later used this knife during her confrontation with Jim Gordon and Barbra Kean.
- Remote control: Nyssa used this remote control linked to the chip in Lee Thompkins brain, in order to control her into assassinating Gordon. Though it failed and Lee's chip was removed from her brain. She also used this remote control to mind-control General Wade and trick Bruce Wayne, Jim Gordon, and Harvey Bullock into falling in her trap.
- "Year Zero" (voice)
- "Ruin" (voice)
- "Pena Dura" (mentioned)
- "13 Stitches"
- "Ace Chemicals" (mentioned)
- "I Am Bane"
- "They Did What?"
- In DC Comics, Nyssa Raatko is a hundreds-year-old supervillain, the daughter of Ra's al Ghul, and the sister of Talia and Dusan al Ghul. She first appeared in Detective Comics #783 (August 2003), and would go on to turn against her father.
- Talia would later go on to have a son with Bruce Wayne.
- Nyssa was previously portrayed by Katrina Law in the CW television iteration of the DC Universe.
- The CW Arrow version was estranged to Ra's al Ghul unlike the version in Gotham.
- Nyssa al Ghul could be considered the true main antagonist behind most of the events of Season 5 such as the destruction of Haven and Bane's actions, given her behind the scenes actions over the plot. This is confirmed when she reveals her true identity and fully confirms herself as the Big Bad of the season.
- It could be argued that Jeremiah Valeska was the main villain, being responsible for No Man's Land as well as being the final main antagonist of the final episode.
- She is the second antagonist that wasn't seen in the final episode of the season the first is the Court of Owls.
- Nyssa al Ghul has a similar role to Talia al Ghul from the 2012 film The Dark Knight Rises, in that she secretly controls Bane, and wants to destroy Gotham due to the actions of Bruce Wayne in killing her father Ra's Al Ghul, while also successfully isolating Gotham from the mainland for a period of several months. Her father's organization is also called The League of Shadows in the series just like the films. In both storylines, she also presents herself as an ally to the main protagonists, and even seemingly provides them with support before revealing her true agenda.
- Nyssa's previous role in the League of Shadows is unknown. Her being the daughter of its leader would have possibly made her an honorary member, but after his death it is unknown if she would have left the organization or if it even exists. Nyssa mentions the organization several times, but she seemingly relies on outside assets to do her bidding, suggesting that she might no longer be part of it, and is simply enacting her own personal crusade against Gotham.