Nyssa al Ghul (Gotham)

"Soon, you and Bruce Wayne will see Gotham destroyed. Then I’ll allow you to die."

- Nyssa al Ghul

"My name is Nyssa al Ghul, and revenge is the beginning of what I want."

- Nyssa to Barbara Kean.

Nyssa al Ghul, also known by her alias Theresa Walker, is one of the two main antagonists (alongside Jeremiah Valeska) of the fifth and final season of FOX TV series Gotham. She is a rogue corrupt government agent who brainwashed Edward Nygma into massacring the Haven and sending Eduardo Dorrance to enact her own mysterious agenda for the city. As it turns out, she is the daughter of Ra's al Ghul and wants to seek vengeance for her murdered father.

She was portrayed by Jaime Murray, who also played Carmilla Pines in Sleepy Hollow, Lila West in DEXTER and the Black Fairy in Once Upon a Time.

Biography
Nyssa is the daughter of Ra's al Ghul and has come to Gotham to take vengeance for her father's death. Years before the destruction of Gotham's bridges, she rescued Eduardo Dorrance, an army officer from the prison Peña Dura and apparently gave him a new purpose.

Following Ra's al Ghul and Jeremiah Valeska's actions of turning Gotham City into a No Man's Land, Theresa had Hugo Strange brainwash and revive both Edward Nygma and Lee Thompkins to do her bidding. According to Eduardo, Walker spent months trying to convince her superiors that Gotham was filled with nothing but criminals and that they needed to step in an wipe them out. He also said she was close to fully winning them over.

When Wayne Enterprises sends a chopper to the city with supplies, Theresa uses Edward to shoot the chopper down with a rocket launcher. Later, she responds to Jim Gordon’s message, saying that she has help on its way to him. After Gordon had a Haven built for hundreds of innocent Gotham civilians, Walker's superiors started believing that the city's criminal underworld was not that bad. Therefore, to try and change their opinions, she has Nygma fire an RPG at the Haven, blowing it up and killing everybody inside.

Walker then sends Eduardo and his Delta Force to hunt down Nygma and have Gordon kill him to ensure his loyalty, while also extracting Strange. Unfortunately, Gordon refuses and escapes, forcing Dorrance to have Nygma kill him. Eduardo informs her of Gordon's escape and their loss of control over Nygma. She sends Lee to the city to ensure that he makes an exchange. Eventually, the press learnt of Walker's actions and she was exposed. Being forced to arrive at Gotham to ensure her plans, she finds Eduardo fatally impaled and gives him a defibrillator, telling him that Strange will "patch him up". She then has Lee kill Gordon, but this also failed.

Trivia

 * She is very similar to Talia al Ghul from the Nolanverse, who is her sister in the canon of the comics. Both of them introduce themselves under an alias as allies to the heroes. Bane arrives and becomes a major threat to the heroes, only for it to be revealed that he was working for Miranda/Theresa, who then reveal themselves as Ra's al Ghul's daughters.
 * Her plot to destroy Gotham and wipe out the criminal element is similar to Ra's al Ghul's plan from the 2011 video game Batman Arkham City, in which a military group begins to try and wipe out the criminals (and any others who stand in the way) in the titular super prison. Like Ra's in that game, Nyssa is afflicted with Hugo Strange who helps her out in her schemes.
 * She shares the role of the main antagonist with Jeremiah Valeska. She and Jeremiah stand in contrast to one another. While Nyssa is a female with a male henchman, Jeremiah is a male with a female henchman. Nyssa is motivated to harm Bruce Wayne out of hatred for him, while Jeremiah is motivated to do so out of a warped love for him. Nyssa and Bane are very serious and threatening antagonists, while Jeremiah and Ecco are jokesters. However, the both of them use their henchmen to do most of their bidding while they hide in the shadows.
 * She also shares the role of the main antagonist with Oswald Cobblepot, as he has influenced most of the season's storyline for it's worst and he is the main antagonist for both Jim and Barbara, and she and Jeremiah are only the main antagonists for Bruce Wayne.