Edna Krabappel

She is a sterotypical "downtrodden schoolteacher" who has had any idealism that she ever had beaten out of her by the sad realities of resource hungry schools and misbehaving children. Despite holding a Master's degree from Bryn Mawr College, she seems poorly educated, a caricature of American public school teachers, as evidenced by the episode when Lisa steals all the teacher's manuals and the teachers are unable to do any work.

Teaches
Bart Simpson, Milhouse Van Houten, Nelson Muntz, and Martin Prince, among others.

Romance
Edna is separated from her husband, who ran off with their marriage counselor. As a result, she severely misses male company, and it is occasionally implied that she feels her biological clock ticking. In early episodes she is portrayed as very sexually aggressive: in the episode Flaming Moe, she tried to pick up both the drummer from Aerosmith and Homer Simpson, even after learning that he was married. She also had a strange relationship with Woodrow a fictional character made up by Bart, in responce to Edna's personal ad he saw in the classifides. In later episodes, though, she develops a secret, but seemingly stable, romantic relationship with Seymour Skinner, the school's principal, which almost makes it to the altar. This is one of the exceedingly few cases where Simpsons characters have apparently undergone personal evolution within the show's history. However, she's also been seen gadding about with Apu, Sideshow Bob, and Comic Book Guy.

Name Origin
Her last name is pronounced ," a play on the fruit "crabapple." Matt Groening admitted in a commentary on the DVD of the first season, it was meant to be a joke that no one called her "crabapple," and indeed no one did-until the real Seymour Skinner came along (see above) and then Milhouse did it once in the fifteenth season (2003-04).

Links
The Simpsons.com