Principal Harlan Dondelinger is the principal of Springfield High School, dating as far back as 1974. He was principal when Homer and Marge were in their final year in the flashback episode "The Way We Was" where he was shown as being a stern figure who appeared to have had several run-ins with Homer and Barney Gumble. He dislikes both of them, believing that they are slackers that will end up in dead end jobs. Dondelinger was right about Homer ending up at a dead end job in the Springfield Nuclear Power Plant, but Barney was able to get a good job as a helicopter pilot. He also appeared at Homer and Marge's reunion in "The Front" and at Artie Ziff's re-creation of the prom in "Half-Decent Proposal". It was obvious that Dondelinger favored Artie over Homer due to the belief that he will be a multimillionaire and do a lot of tasks that Homer would never do.
In Take My Life, Please, Dondelinger infuriated Homer when he revealed that he hid the ballot box with the help of two student athletes (one being Vance Connor) whom came up with the idea of putting Homer's name on the ballot as a joke so when he lost, everyone can laugh at him(which worked out well). He paid Lenny and Carl to hide the real ballot box containing Homer's name to ensure that he loses. Dondelinger, Vance and another student were presumably blackmailed by Marge and her children to do the right thing and put Homer's name in a plaque on the Springfield Wall of Fame, by threatening to reveal their dirty misdeeds to everyone in Springfield which would have brought humiliation to the men with their downfall and eventual arrest.
Aside from his acting as principal for Springfield High School, he also acted as a teacher at the Adult Education Annex in "The Front," where he specifically taught remedial Science 1A (and more specifically, Homer's class). In "The Front," Dondelinger explains that his wife had recently passed away, so he chose to take up teaching night classes as way to ease his newfound loneliness.
- Episode – "The Way We Was" (flashback)
- Episode – "The Front"
- Episode – "Who Shot Mr. Burns? (Part One)"
- Episode – "Half-Decent Proposal" (Brief appearance)
- Episode – "She Used to Be My Girl" (flashback)
- – The Simpsons Movie
- Episode – "That '90s Show"
- Episode – "Take My Life, Please"
- Episode – "Treehouse of Horror XXIII" (Brief appearance)