Ms. Bitters is a minor villain in the animated series Invader Zim. She is the teacher of Zim's and Dib's class at Skool. A tall, slender old woman of unknown origin or age, she is a very grouchy teacher, who has devoid of any positive emotion and full of demonic hatred for children. Ms. Bitters is voiced by the late Lucille Bliss. Her first name is unknown.
In some early episodes, she appears to be covered in cockroaches. When her students displease her, she habitually looms over them, menacingly, with clawed hands and bared teeth, feeding the possibility that she is inhuman. Details on her history is unknown.
Whatever she is, she cannot survive in direct sunlight, as seen in The Voting of the Doomed. In this same episode, she is wearing a black cloak like a vampire, thought to protect her from the sun. She greatly dislikes children, and has expressed frustration at school over-crowding, as well as disdain for traditional holidays such as Halloween and Valentine's Day (although dislike for the latter could be justified, considering an unknown event in the past changed the Valentine's Day tradition from giving out chocolate and cards to giving "Valentine meat slabs"). In the Halloween Spectacular of Spooky Doom, she is revealed to have an even more demonic doppelgänger in an alternate dimension: A gremlin-like creature known as Nightmare Bitters, who is after Dib's head. She tried to get into Dib's true world, but went back after seeing how