All events that happened in 1998.
- 3rd: "King of the Hill" aired for the first time.
- 10th: "Lost Our Lisa" aired for the first time.
- 17th: "Natural Born Kissers" aired for the first time.
Season 9 ended.
- 18th: The Simpsons: Against the World was released on VHS for the United Kingdom.
- 28th: Phil Hartman, voice of Lionel Hutz and Troy McClure, died.
- 28th: Bill Williams, the original designer for The Simpsons: Bart's Nightmare, died.
- 25th: "Treehouse of Horror IX" aired for the first time.