Mrs. Stoller was a substitute teacher hired as a scab worker during "Lucky Strike". She is worryingly senile, believing she's teaching a class full of very large first-graders, marking down Kevin Thompson for not putting his 'real name' of Cubie ("Q.B.") on his paper, and managing to forget Daria was called Daria within a day of making the deliberate decision to call her Darlene instead (Daria sounded like a "hippy name"), which even allowed Daria to trick her when Ms. Li called her to her office, leaving the class saying to Mrs. Stoller that she was going to look for "Daria". To be nice to Jane, Daria writes her a note from "Miss Darlene" to get her out of Stoller's classes.
She makes a rare appearance in TAG's "It Slipped Through My Hands, Like a Shadow, Like a Dream", where she's the teacher for a developmentally disabled version of Daria, and Kristen Bealer's "Blood, Sweat, and Cheers", where O'Neill didn't come back after "The F Word".