Ecco

Ecco is the secondary antagonist in the final episodes of the fourth season of the TV series Gotham. She is Jeremiah Valeska/The Joker's assistant and henchwoman.

She is portrayed by Francesca Root-Dodson.

History
At some point in her life, Ecco becomes the assistant to Jeremiah Valeska, under the alias Xander Wilde, and acts as his proxy, handling his public business herself.

Jeremiah sends Ecco to capture Jerome so he can be held inside a cage. Jim Gordon and Harvey Bullock ask him to hand Jerome to the GCPD, but Jeremiah refuses. Jerome however sends his henchmen to hypnotize Ecco and sends her to kill Jim Gordon and Harvey and to bring Jeremiah to Jerome.

As Jerome's followers gather up after his death, a woman dressed as a Mummer in a jester costume shows up on her motorcycle at the cemetery in which they are all gathered. The leader of the troupe tells her the gathering is invitation only and tries to kill her by throwing a knife at her, only for her to block it with her wrist and blow an air horn. Gaining their attention with the noise, she holds up a voice recording to the horn, projecting a message from Jerome, giving the cult instructions to dig him up.

Jim Gordon shows up to Jeremiah's bunker and a video of Jerome begins to play on the screen. The Mummer shows up points a gun towards Jim's head and Jerome tells him not to mind her. Jim knocks the gun away and tries to fight the Mummer, but she puts up a fight back. Jerome begins being choked on the monitor. Jim gets the upper hand on the Mummer and knocks her out. He removes her mask to reveal Ecco as the Mummer, while on the screen "Jerome" is revealed to be Jeremiah with makeup. Ecco sneaks away and locks Jim inside the bunker, which explodes.

Later, Jeremiah, now with pale white skin, arrives at Wayne Enterprises. The guards ask him if he's alone and he reveals Ecco behind him, who shoots the guards. The two of them steal the keycards and use them to enter the room where all of the self perpetuating generators that Jeremiah wants to use as bombs are stored.

Personality
Ecco is extremely devoted to Jeremiah. At first, she seems calm, friendly, and professional. However, after Jeremiah becomes the Joker, she reveals a more psychotic personality, killing two guards for him and being willing to act as his accomplice in destroying Gotham.

Trivia

 * She is seemingly based on Harley Quinn or an allusion/origin to the character.