Played by: David Hyde Pierce
Episode: “Brother from Another Series” (Season 8, Episode 16)
Claim to Fame: The man we know best as Niles truly nails this role through and through, but the Cousin Merle exchange will go down in the comedic history books.
Played by: Beverly D’Angelo
Episode: “Colonel Homer” (Season 3, Episode 20)
Claim to Fame: She’s one half of an affair that feels, even its simplicity, like a legitimately moving tribute to the difficulties of maintaining a long-term relationship.
Played by: Dustin Hoffman
Episode: “Marge vs. the Monoral” (Season 4, Episode 12)
Claim to Fame: His ultimate lack of contribution to the efforts to stop the runaway monorail.
Played by: Dustin Hoffman, although credited as “Sam Etic”
Episode: “Lisa’s Substitute” (Season 2, Episode 19)
Claim to Fame: Bergstrom (and Hoffman) happily tap-dancing around the fact that he is, quite obviously, Jewish.
Played by: Woody Harrelson, George Wendt, Ted Danson, Rhea Perlman, and John Ratzenberger
Episode: “Fear of Flying” (Season 6, Episode 11)
Claim to Fame: Norm going ape on Woody in a drunken stupor… something that should have happened a long time ago.
Played by: Johnny Cash
Episode: “El Viaje Misterioso de Nuestro Jomer (The Mysterious Voyage of Homer)” (Season 8, Episode 9)
Claim to Fame: Cash’s performance as the psychedelic talking coyote is actually played pretty straight. He does help Homer reevaluate his life and relationship with Marge.
Played by: John Waters
Episode: “Homer’s Phobia” (Season 8, Episode 15)
Claim to Fame: One line of dialogue that is altogether funny, poignant, and terribly sad: “I won your respect, and all I had to do was save your life. Now, if every gay man could just do the same, you'd be set.”
Played by: Michael Jackson, although credited as “John Jay Smith”
Episode: “Stark Raving Dad” (Season 3, Episode 1)
Claim to Fame: Although Leon/Michael’s incredibly catchy “Happy Birthday Lisa” song is an episode highlight, we can’t call that Jackson’s claim to fame since it wasn’t he but singer Kipp Lennon who performed the number (for convoluted legal reasons).
Played by: Patrick Stewart
Episode: “Homer the Great” (Season 6, Episode 12)
Claim to Fame: Something about Stewart’s indomitably classy accent calling for drunken ping-pong is especially joyful.
Played by: Don Mattingly, Jose Canseco, Roger Clemons, Mike Scioscia, Ken Griffey Jr., Steve Sax, Ozzie Smith, Darryl Strawberry, and Wade Boggs (as themselves)
Episode: “Homer at the Bat” (Season 3, Episode 17)
Claim to Fame: Considering the fact that this is widely considered one of the very best Simpsons episodes ever, that’s a tough call… but we’ll have to give it to Don Mattingly eagerly welcoming Mr. Smithers into his home, or perhaps Ozzie Smith falling into a mysterious parallel dimension