Mervin Monroe - Agnes Skinner

Agnes Skinner, voiced by Tress MacNeille is the mother of school principal Seymour Skinner and first appeared in the first season episode "The Crepes of Wrath" as an old woman who embarrassingly calls her son "Spanky". However, as episodes progressed, the character turned bitter. She is very harshly controlling of Seymour, and treats him like a mother would a small child, once grounding him because he did not say who was at the door after answering it, when it was "The Sugarman". She hates Edna Krabappel. Agnes has married a total of four times, once with Skinner's father, Sheldon Skinner, and following Sheldon's death she then married three more times, each time, to a tow truck driver. Several Springfield residents (including the Simpsons) are afraid of her. When Agnes' real son, "the real Seymour Skinner" arrives in Springfield, Agnes turns him away, unhappy with her new living situation, largely because the true Seymour Skinner is a man who can stand up to Agnes and make his own decisions. Although she appears to not care for the fake Skinner, it turns out she really loves him, although she denies it in "Large Marge".

Agnes's first name was revealed in the seventh season episode "Bart the Fink". Before that, the character was known as "Mrs. Skinner". In the beginning of the series, the writers made several references to Agnes and Seymour's relationship being similar to that of Norman Bates and his mother's in the film Psycho. In "Boy Meets Curl," it is revealed that some of Agnes' resentment to Seymour may have derived from even before Seymour was born — during the 1952 Summer Olympics in Helsinki, Agnes competed in the pole vaulting event while 9-months pregnant. When Seymour makes his first kick, he hits the bar, thus, making Agnes lose and subsequently crushing her dreams. However, this would contradict the earlier episode when it is revealed that Seymour isn't her birth son.