This is a list of notable guest stars who appeared in the American television sitcom 3rd Rock from the Sun throughout its six season run.
- Harry Morgan - (3 episodes, seasons 1 & 2) playing Professor Suter, an elderly colleague of Dick and Mary
- Martha Stewart - playing herself.
- Phil Hartman - (seasons 1 & 3) playing a camp cosmetics store worker and Randy, Vicki Dubcek's ex-lover.
- Jane Lynch - playing Tommy's science teacher, Ms. Koppel
- John Mahoney - playing Leonard Hamlin, a rude, sexist professor
- Lauren Graham - playing Laurie Ives
- John Raitt - playing Singing Truck Driver
- Dennis Rodman - playing himself; it is revealed that he is actually another alien.
- George Takei - playing himself at a sci-fi convention.
- Al Franken - playing Harry's opponent in the City Council election.
- Mike Ditka - playing Coach Mafferty; coach for Pendelton Badgers.
- Mark Hamill - playing himself.
- Christine Baranski - playing Sonja Umdahl
- Randy Newman - playing himself.
- Roseanne Barr - playing Dick's forced-wife Janet
- Leigh McCloskey - playing Matthew, a yoga instructor.
- Elaine Stritch - (seasons 3 & 6) playing Martha Albright, Mary's mother.
- George Grizzard - (seasons 3 & 4) playing George Albright, Mary's Father.
- Cindy Crawford - playing Mascha, a Venusian woman dating Harry.
- Angie Everhart - playing Chloe, a Venusian woman dating Tommy
- Dom DeLuise - playing the father of Dick's student Bug.
- Peter DeLuise - playing Franky.
- John Cleese - (seasons 3 & 6) playing Professor Liam Neesam, a hostile alien.
- Sam Lloyd - playing Eddie, a man Dick helps.
- Laurie Metcalf - playing Jennifer Ravelli, a teacher of comparative literature.
- Kathy Bates - playing Charlotte Everley, an alien hunter.
- Gil Christner - playing Carl, a Nobel Laureate.
- William Shatner - (seasons 4 & 5) playing The Big Giant Head (a.k.a. Stone Phillips).
- Aaron Paul - (Season 4) Playing the Junior Prom King & Queen announcer.
- Kurtwood Smith (Season 4) Playing Dick's "cousin" Jacob when they attend a Solomon family reunion
- Bryan Cranston - Plays a Neil Diamond Impersonator (whom Sally kisses) Season 4 Episode 14.
- Billy Connolly - playing an actor who is playing the part of Inspector McAffrey.
- David Hasselhoff - playing a plastic surgeon.
- Jonathan Frakes - playing Larry McMichael, the husband of Mary's friend Gwen.
- Genie Francis - playing Gwen McMichael, the wife of Larry McMichael.
- Chyna - playing Janice, a police officer
- Miguel Ferrer - playing Jack McMannus, a government agent.
- Alan Cumming - playing Angus 'The Hole' McDuff, a hole expert.
- Enrico Colantoni - playing Frank, an ex-student of Mary's.
- Megan Mullally - playing Renata Albright, Mary's sister.
- Elvis Costello - playing himself.
- Mark McKinney - Playing a new alien that stumbled through the Solomon's closet door.