In 2006, the internet site IGN.com published their list of the Top 25 guest appearances.
The list left off anyone who voices on the show so often that they're nearly regular cast members, such as Phil Hartman, Kelsey Grammer, Marcia Wallace and Joe Mantegna, although it did include Jon Lovitz.
NOTE: The list was published in 2006 (prior to Season 18, and some of the guest stars listed here have appeared since then. The episodes since then are not included.
- Albert Brooks as Cowboy Bob ("The Call of the Simpsons"), Jacques ("Life on the Fast Lane"), Brad Goodman ("Bart's Inner Child"), Hank Scorpio ("You Only Move Twice") and Tab Spangler ("The Heartbroke Kid")
- Mark Hamill as himself and Leavalle ("Mayored to the Mob"
- Dustin Hoffman as Mr. Bergstrom ("Lisa's Substitute")
- Bette Midler, Hugh Hefner, Johnny Carson, Luke Perry and the Red Hot Chili Peppers as themselves ("Krusty Gets Kancelled")
- Michael Jackson as Leon Kompowsky ("Stark Raving Dad")
- Winona Ryder as Allison Taylor ("Lisa's Rival")
- James Earl Jones as Maggie Simpson, Serak the Preparer, the mover and the Narrator ("Treehouse of Horror", "Treehouse of Horror V" and "Das Bus")
- Jon Lovitz as multiple characters (multiple episodes)
- John Waters as John ("Homer's Phobia")
- Ringo Starr as himself ("Brush with Greatness"), George Harrison as himself ("Homer's Barbershop Quartet") and Paul McCartney as himself ("Lisa the Vegetarian")
- Leonard Nimoy as himself ("Marge vs. the Monorail" and "The Springfield Files")
- Ron Howard as himself ("When You Dish Upon a Star" and "Hello Gutter, Hello Fadder")
- Elizabeth Taylor as Maggie Simpson ("Lisa's First Word")
- Johnny Cash as The Space Coyote ("El Viaje Misterioso de Nuestro Jomer (The Mysterious Voyage of Homer)")
- The Ramones as themselves ("Rosebud")
- Stephen Hawking as himself ("They Saved Lisa's Brain" and "Don't Fear the Roofer")
- Roger Clemens, Wade Boggs, Ken Griffey, Jr., Steve Sax, Ozzie Smith, José Canseco, Don Mattingly, Darryl Strawberry and Mike Scioscia as themselves ("Homer at the Bat")
- Spinal Tap (Harry Shearer as Derek Smalls, Christopher Guest as Nigel Tufnel and Michael McKean as David St. Hubbins) ("The Otto Show")
- Mel Gibson as himself ("Beyond Blunderdome")
- Ted Danson as Sam, Woody Harrelson as Woody, Rhea Perlman as Carla, George Wendt as Norm and John Ratzenberger as Cliff ("Fear of Flying")
- James Taylor as himself ("Deep Space Homer")
- Tito Puente as himself ("Who Shot Mr. Burns? (Part One)" and "Who Shot Mr. Burns? (Part Two)")
- Peter Frampton, The Smashing Pumpkins, Cypress Hill and Sonic Youth as themselves ("Homerpalooza")
- Aerosmith as themselves ("Flaming Moe's")
- Glenn Close as Mona Simpson ("Mother Simpson" and "My Mother the Carjacker")
- Goldman, Eric; Dan Iverson, Brian Zoromski (2006-09-05). Top 25 Simpsons Guest Appearances. IGN.com. Retrieved on 2008-03-25.