Erin (Sophie's Mother)

Erin is a woman who has a daughter named Sophie, whose father is Krusty the Clown. Sophie was born as the result of a wartime affair between Erin and Krusty. Though nameless in the series, her named is revealed to be Erin in The Krusty Book of the Simpsons Library of Wisdom series.

History
During the Gulf War, Erin was serving as a soldier when she met Krusty, who was performing with a USO tour. They hit it off immediately and had a romantic night of passion. In the morning, Erin remembered her mission—to assassinate Saddam Hussein -- and quickly left the tent where she and Krusty had spent the night, in spite of Krusty's telling her not to go. Erin was aiming a rocket launcher at Saddam when Krusty caught up to her and protested that she couldn't kill Saddam because he was half of Krusty's act. Just as Erin was about to fire, Krusty tackled her, making her miss and ruining her mission.

As a result of that experience, Erin came to hate clowns, and filled her house with artwork showing them being tortured and killed.

Trivia

 * Erin doesn't allow Sophie to watch television, believing that it could lead to dating celebrities and that they're lowlife, boozing, floppy shoe-wearing, degenerates.