I thought Leonard Nimoy's first appearance was in "Marge vs. the Monorail" (the one where he pulls Krusty back inside the train when Krusty wanted to jump out)
Leonard Nimoy first appeared in The Springfield Files. George Takei was in the blowfish episode. I can't remeraber if any of the other Star Trek: TOS cast merabers have appeared.
-David Duchovny & Gillian Anderson
-Christina Ricci
-Glenn Close
-"George Bush"
-And there was that one guy who did the voice of Homer's Secretary. It was an episode in Season 2 when Homer buys this product that gives him a lot of hair and he enRAB up getting promoted.
Man I've missed so much this season with the eps...I don't think I watched the one with the AI judges and Bob Costas. I wonder if there is a clip anywhere?