- Steve Landesberg - Gary (voice)
- Julia Louis-Dreyfus - Heather Worthington (voice)
- Ken Hudson Campbell - Crazy Lou (voice)
- Jeffrey Tambor - Hank Hibler (voice)
- Dan Castellaneta - Zabar (voice)
- Michelan Sisti - Additional Dinosaur Performer / Cavepeople
- Stephen Caffrey - Scabby (voice)
- Harold Gould - Dinosaur Chief (voice)
- Sally Kellerman - Pteranodon (voice)
- Robert Picardo - Ted (voice)
- Robert Picardo - Muse (voice)
- Robert Picardo - Clerk (voice)
- Brian Henson - Arthur Rizzic (voice)
- Brian Henson - Aubrey Molehill (voice)
- Harry Shearer - Narrator (voice)
- Perry Anzilotti - Chang Chang
- Jeff Chayette - Ling Ling
- Julie Maddalena - Caveman's Wife
- Peter Bonerz - Insurance Agent (voice)
- Steven Banks - Folk Singer (voice)
- Michael Earl - Boy Contestant (voice)
- Michael Earl - Refrigerator Monster (voice)
- Paula Marshall - Cavewoman
- Tim Doyle - General Chow (voice)
- David Wohl - Bob (voice)
- Mimi Kennedy - Glenda Molehill (voice)
- Michael Dorn - WeSaySoCorp Announcer (voice)
- Michael Dorn - Television Announcer (voice)
- Michael Dorn - Elder in Chief (voice)
- Michael Dorn - Solomon The Great (voice)
- Jack L. Harrell - Mr. Harold Heffer (voice)
- David Leisure - Mr. Teddy Wolfe (voice)
- Jason Alexander - Gus Molehill (voice)
- Jason Alexander - Sexual Harris (voice)
- Jason Alexander - Stu (voice)
- Jason Alexander - Grown Baby (voice)
- Jason Alexander - UFO! Host / Announcer (voice)
- Jason Alexander - The Job Wizard (voice)
- Jason Alexander - General H. Norman Conquest (voice)
- Heather McPhaul - Caller (voice)
- Tony Shalhoub - Jerry Valentine (voice)
- John Vernon - Mr. Ashland (voice)
- William Schallert - Wesayso Scientist (voice)
- Edie McClurg - Shopper (voice)
- Richard Portnow - Mel Luster (voice)
- Buddy Hackett - Louie (voice)
- George Gaynes - Elder in Chief (voice)
- G.W. Bailey - Sarge (voice)
- Kirk R. Thatcher - Timmy (voice)
- Kirk R. Thatcher - Wereman (voice)
- Gary Owens - Narrator (voice)
- Fred Travalena - Bob Hack (voice)
- Jason Bernard - Edward R. Hero (voice)
- Paxton Whitehead - Sir David Tushingham
- Paxton Whitehead - Judge (voice)
- Shaun Baker - Lingo (voice)
- Michael Richards - Director (voice)
- Richard Simmons - Richard Simmons Dinosaur (voice)
- Kate McGregor-Stewart - Neighbor No. 3 (voice)
- Suzie Plakson - Monica Devertebrae (voice)
- Suzie Plakson - Monica Devertebrae / Sally (voice)
- Suzie Plakson - Elder #3 (voice)
- Suzie Plakson - Thighs of Thunder (voice)
- Charles Kimbrough - Dr. Ficus (voice)
- Wendie Jo Sperber - Wendy Richfield (voice)
- Sam McMurray - Roy Hess (voice)
- Sam McMurray - Roy Hess / Buddy Glimmer (voice)
- Sam McMurray - John (voice)
- Sam McMurray - Andre (voice)
- Sam McMurray - Dolf (voice)
- Sam McMurray - Roy Hess / Stan (voice)
- Sam McMurray - Absolute Proof Laboratories Scientist (voice)
- Sam McMurray - Wesayso Interviewer (voice)
- Sam McMurray - Roy Hess / The Doctor (voice)
- Pat Crawford Brown - Stenographer (voice)
- John Glover - Lucius (voice)
- John Glover - Prosecutor (voice)
- John Glover - Babysitter (voice)
- Allan Trautman - Mr. Pulman (voice)
- Allan Trautman - Moola the Cash Cow (voice)
- Allan Trautman - Monster (voice)
- Allan Trautman - Georgie (voice)
- Allan Trautman - Hank (voice)
- Allan Trautman - Lieutenant / Rocco (voice)
- Allan Trautman - Mug Salesman (voice)
- Allan Trautman - Maurice (voice)
- Allan Trautman - Narrator / Officer Brazelton (voice)
- Allan Trautman - Dr. Elliot Piaget (voice)
- Allan Trautman - Mr. Otto Lynch (voice)
- Julianne Buescher - Caroline Foxworth (voice)
- Julianne Buescher - The Smoo Show Singers (voice)
- Julianne Buescher - Simone Poupon (voice)
- Thom Sharp - Larry (voice)
- Thom Sharp - Chef (voice)
- Thom Sharp - Frank (voice)
- Thom Sharp - Richard (voice)
- Thom Sharp - Walter Sternhagen (voice)
- Thom Sharp - Decker (voice)
- Thom Sharp - Ed (voice)
- Thom Sharp - Bert (voice)
- Thom Sharp - Ticket Guy (voice)
- Steve Whitmire - Sonny (voice)
- Steve Whitmire - Woody (voice)
- Steve Whitmire - Mr. Mason Dixon (voice)
- Julius Carry - Mudbelly (voice)
- Jon Polito - Ty Warner (voice)
- Jessica Lundy - Mindy (voice)
- Jessica Lundy - Sitcom Wife (voice)
- Jessica Lundy - Caroline Foxworth (voice)
- Jessica Lundy - Vendor (voice)
- Conchata Ferrell - Shelly (voice)
- Tim Curry - Henri Poupon (voice)
- Tim Curry - Jean-Claude (voice)
- Tim Curry - Pterodactyl (voice)
- Tim Curry - The Devil (voice)
- Tim Curry - Winston (voice)
- Tim Curry - Chief Elder (voice)
- Tim Curry - Fox Jacket (voice)
- Bruce Lanoil - Francois Jean-Marie Poupon (voice)
- Bruce Lanoil - Judge (voice)
- Christopher Meloni - Spike (voice)
- Florence Stanley - Grandma Ethyl Phillips (voice)
- David Warner - Spirit of the Tree (voice)
- Sherman Hemsley - B.P. Richfield (voice)
- Michael McKean - Police Chief Parish (voice)
- Michael McKean - Mr. Myman (voice)
- Michael McKean - Kyle (voice)
- Michael McKean - Hank (voice)
- Michael McKean - Ed (voice)
- Michael McKean - Les (voice)
- Michael McKean - Officer Bettleheim (voice)
- Michael McKean - Inspector (voice)
- Michael McKean - Ansel (voice)
- Michael McKean - Dr. Herder (voice)
- Michael McKean - Bryant (voice)
- Michael McKean - Guy in the Lab Coat (voice)
- Joe Flaherty - Chief Elder (voice)
- Joe Flaherty - Elder (voice)
- Glenn Shadix - Monster (voice)
- Glenn Shadix - Ray (voice)
- Susan Norfleet - Pearl Sinclair (voice)
- Joyce Kurtz - Brigitte (voice)
- Joyce Kurtz - Katie (voice)
- Ed Asner - Evil Georgie (voice)
- Ernie Anderson - Announcer (voice)
- Brian Henson
- Jeff McCracken
- Michael Jacobs
David Warner interpreta a Spirit of the Tree (voice) en la serie.
Wendie Jo Sperber interpreta a Wendy Richfield (voice) en la serie.
Jeffrey Tambor interpreta a Hank Hibler (voice) en la serie.
Michael Dorn interpreta a Television Announcer (voice) en la serie.
Conchata Ferrell interpreta a Shelly (voice) en la serie.
Edie McClurg interpreta a Shopper (voice) en la serie.
Tony Shalhoub interpreta a Jerry Valentine (voice) en la serie.
Jon Polito interpreta a Ty Warner (voice) en la serie.
Richard Portnow interpreta a Mel Luster (voice) en la serie.
Jason Alexander interpreta a UFO! Host / Announcer (voice) en la serie.
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