The AntAgonizer

Tanya Christoff AKA the AntAgonizer is a 27-year old quest character in Fallout 3 located in the Canterbury Commons in 2277. She possesses control over giant ants and is fighting her nemesis, the Mechanist. She is dressed in an ant costume, comically emulating a supervillainess.

Background
Talking to Joe Porter reveals that her name is Tanya Christoff and also reveals her background.

Her family was killed by ants when she was young, and she has since taken on the belief that ants are superior to humans, citing their instinctual willingness to work together to accomplish goals unlike humans' desire to kill one another through warfare.

A terminal in Hubris Comics contains a letter to the editor that mentions the AntAgonizer as one of Grognak the Barbarian's villains. The letter expresses sadness as the villain was "never developed fully". The AntAgonizer's background story matches the comic book and she was to appear in Grognak and the Ants of Agony, but the comic was thrown out due to bad writing.

Quest: The Superhuman Gambit
Uncle Roe offers a quest to stop the AntAgonizer's battle with the Mechanist.

Random Encounter: Wrath of the Antagonizer
If you side with the AntAgonizer during The Superhuman Gambit, there is a random encounter later on in which you find the AntAgonizer and a group of her ants attacking a group of Wastelanders. The AntAgonizer is neutral towards you, but will turn hostile if you attack her ants.

Behind the scenes
In the Polish version of the game, she is called "Entomologia" (Entomology) as a reference to Entomologia Motylkowska, a character in comic books by Tadeusz Baranowski.

Appearances
Tanya Christoff (The antagonizer) only appears in Fallout 3.