The puppets of the characters were designed by The Great Jones Studio, New York under the supervision of Kermit Love. The puppet designers and builders consisted of James Kroupa, Robert Lovett, Christoper Lyall, John Orberg, and Matthew Stoddard.
The show is about three young singers (Francine, Danny, and Roy) who are brought to a habitable asteroid in space called Coasterville by a clown named Baxter who pilots the "space coaster", a roller coaster-like spaceship. The asteroid is populated by strange-looking, wise-cracking puppet characters such as Goriddle Gorilla, Knock-Knock the Woodpecker, Edison the Elephant, and Gary Gnu (who hosts The Gary Gnu Show). Baxter is forever on the run from M.T. Promises, a nefarious ringmaster who plans to re-capture Baxter and return him to the circus he worked at before he escaped. Each episode ends with a different life lesson, and various celebrity guest stars (such as Mark Hamill of Star Wars fame and composer Marvin Hamlisch) occasionally dropped by.
In each episode, Roy shows a short film on his portable, fold-up TV, often featuring segments from La Linea, an Italian animated series about a little man who is drawn (using a single line) at the beginning of the segment and then springs to life, communicating with his animator through high-pitched Italian mixed with gibberish. Francine, Roy, and Danny sing a song together as the Space Coasters in each episode (sometimes originals like "Wacky Talk", sometimes older songs like "Be a Clown" or covers of '60s and '70s hits), and the various puppet characters often sing songs as well. A few years into the show's run, the MTV-like "Rockin' with Rory" segment began where a DJ named Rory would introduce "Danny and the Space Coasters" performing cover tunes. While the action was mostly videotaped on the space set, it wasn't unusual for the characters to venture down to Earth for filmed musical numbers.
Francine (played by Emily Bindiger) - Francine, or Fran for short, is a beautiful young woman from a fishing village on the East Coast and is the leader of the Space Coasters where she plays the guitar. She also acts as Baxter's second-in-command.
Danny (played by Chris Gifford) - Danny is from a small midwestern town, a member of the Space Coasters, and Francine's second-in-command. He plays the drums in the Space Coasters.
Roy (played by Ray Stephens) - Roy is from the big city and a member of the Space Coasters where he plays the keyboards. He is also a good poet. Roy would show clips and short films on his hand-held magic screen.
Baxter (performed by Francis Kane) - A large, gentle clown who once worked for M.T. Promises in an apparently slave-like situation at M.T.'s circus and lives in fear of ever going back. He now pilots the space coaster, taking the characters from Earth to the asteroid. He can magically disappear by twirling around, a talent he uses to escape M.T.'s attempts to catch him and bring him back to his circus. Whenever the gang wants to leave on a field trip, he always exclaims "The Great Space Coaster is ready for takeoff!" When the gang assembles, he always says, "Get on board for a magical trip. And where we land this time is anybody's guess." He sometimes plays the "baxophone" (an instrument similar to a saxophone) with the Space Coaster Band.
Goriddle Gorilla (performed by Kevin Clash) - A gravel-voiced orange gorilla-like creature. He has a tendency to be rude, obnoxious, nosy, lazy and a nuisance, but somehow the gang on the asteroid seem to like him just the way he is. He and Knock Knock introduce Gary Gnu whenever "The Gary Gnu Show" segment comes on. He is roommates with Edison the Elephant.
Knock Knock the Woodpecker (performed by John Lovelady in 1981-1983, Noel MacNeal in 1983-1986) - A prissy pink bird who lives in the hollow of a tree and tells a lot of knock-knock jokes. She alongside Goriddle Gorilla occasionally introduces Gary Gnu whenever the "Gary Gnu Show" segment comes on. Knock Knock also intros the "Book of the Week in Review" segments by saying "And here's Gary Gnu with the Book of the Week in Review" usually waking Gary Gnu from a nap. Knock Knock also uses her sense of humor at times to give Goriddle Gorilla a taste of his own medicine.
Edison the Elephant (performed by John Lovelady in 1981-1983, Jim Martin in 1983-1986) - A strange, large robotic-looking elephant with a segmented, hose-like, ever-moving trunk and semi-transparent, fan-like ears, whose voice is an echo. He loves plants and tends a large garden. He and Goriddle Gorilla are roommates.
Gary Gnu (performed by Jim Martin) - A green gnu-like newscaster who hosts "The Gary Gnu Show" each episode and is well known for his catchphrase "No gnews is good gnews with Gary.... Gnu." He would add a guttural "g" sound to the beginning of any word he spoke which normally began with an "n", such as "gnews" for "news" and "gnaturally" for "naturally". Whenever introduced by either Goriddle Gorilla or Knock Knock, the introduction is always "And Now For Something Really Gnew, Here's Gary Gnu." The only difference is that Goriddle always says "WOW!" each time he introduces Gary Gnu. Gary always begins by saying, "This is Gary Gnu, and the 'No Gnews Is Good Gnews Show'. The Only TV Gnews Program Guaranteed To Contain No Gnews Whatsoever." In his segments, Gary introduced and narrated film clips of people in silly situations, weird sporting events, unlikely inventions, etc. Gary's unusual speaking style was inspired by the 1957 Flanders and Swann song, The Gnu, which told the story of a gnu in a zoo who spoke much as Gary did, adding a "g" sound to the beginning of various words. Gary actually sang the song in one episode. Gary Gnu's gnewscasts were punctuated by comments and jeers from the filming crew with the crew having different items or things thrown onstage as a way of misinterpreting one of words that Gary says in his gnews. Occasionally, he would be set up for a practical joke after one of his jokes as the crew would call him a "turkey" followed by the dropping of a paper turkey (with Gary's picture taped over the face) onto Gary Gnu's head with a gobbling sound effect.
Speed Reader (played by Ken Myles) - A young man who appears on the "The Gary Gnu Show." He can allegedly read incredibly fast, zipping through an entire book (usually a recently published novel for young readers) in seconds and then offering a short review. Before a reading, he'll warm up by doing "push-ups" with his eyelids (blinking rapidly and moving his eyes around). Before each Speed Reader appearance, there would be a short film and "Speed Reader" song showing Speed Reader reading fast. Gary Gnu would sing the song along other people would shout "Speed Reader Speed Reader".
The Huggles - Small, furry creatures who have stories read to them by Baxter (usually about "Bamba the Barbarian"). They consist of Fluffy (performed by Pam Arciero), Puffy (performed by Pam Arciero), and Scruffy (performed by Kevin Clash). They also have a little sibling named Baby Huggle (performed by Pam Arciero) that appears later on. Baxter brought the Huggles to the asteroid after he found their eggs in space. As their intro song put it, Baxter "brought 'em home to hatch 'em, and now they're here to stay...." Introduced a few years into the series' run, the extreme (some would say excessive) cuteness of the these characters was an attempt to appeal to a younger demographic. Their catchphrase was "Hey, what's snappenin'?!"
Rory (performed by Kevin Clash) - A wild-looking lion-like VJ. He appeared a few years into the show's run as the host of "Rockin' with Rory," a segment featuring music videos by the Space Coasters, typically performing covers of '60's hits. He would often run late and show up in his pajamas where he would make a claim about why he was late when the crew asks "Late Again Rory! What’s the story?" Rory replies, “You won’t believe this but..” and launches into one of his many wild excuse for being late. The crew wouldn't believe it. Then Rory would quote "believe this" as he introduces the Space Coasters' act.
Baffle (performed by Jim Martin) - A furry, horned magical alien from the neighboring planet Blip (where everything is either backwards or upside down or just plan weird) who appeared a few years into the show's run. She casts spells by chanting the phrase "Miki Pooka Tiki". Baffle can see 12 minutes into the future. He loves to give free advice for when the residents of Coasterville have a problem, they pay Balffe a visit. Unfortunately his advise is often so silly or cryptic that they usually have to solve the problem themselves.
Big Jock Ox (performed by Kevin Clash) - An ox-like character who appeared a few years into the show's run. Big Jock Ox would often appear on "The Gary Gnu Show."
M.T. Promises (performed by Jim Martin) - A nefarious, bulgy-eyed, top hat-wearing, caped, ringmaster who is the primary antagonist of the series. He has always been scheming to capture Baxter the Clown and take him back to the circus. More silly than sinister, he sweeps onto and off the set accompanied by evil circus music and his farewell is always a sarcastic "have a nice day." M.T. Promises has a full length mirror that talks back to him. The mirror serves as his conscience and frequently gets him so mad that he tires to smash the “Good For Nothing” mirror with a swift kick, but he hurts his foot and not the mirror. Whenever M.T. Promises isn't trying to recapture Baxter, he would often try to swindle the characters by selling them broken stuff for money, play dirty pranks on the characters, and try to break up the Space Coasters by inflating the ego of their members. One episode had M.T. Promises helping out the Space Coasters' telethon to get the money to replace the worn-out instruments.
Jim Martin - Gary Gnu, M.T. Promises, Baffle, Edison the Elephant (1983-1986)
As of 2012, Jim Martin launched a campaign to help raise money to finance the preservation of as many episodes of The Great Space Coaster as possible. The original master tapes had been purchased by Tanslin Media, but it is very costly to transfer, convert, and store video tape into digital media, with a cost of up to $350 for one episode. It was estimated that it would cost anywhere between $35,000 to $40,000 to preserve all 250 episodes of the series, but knowing such a goal wasn't plausible, Martin set a goal to preserve $2,000 worth of episodes. As of May 21, 2012, the donations exceeded the goal, and Jim Martin was able to raise $3,500 to preserve as many episodes as possible. Presently, there are also legal issues that are preventing the series from being released publicly for home entertainment.
In the Family Guy episode "I Take Thee Quagmire", Peter Griffin remembers the time he had on the magical ride of the space coaster. He is then seen picking up five children and traveling through the galaxy to take on the journey while the theme song plays. Seven years later, Peter has found himself lost with four older children who have outgrown their clothes. While Peter is trying to read a map, Ricky (one of the "children") tries cheering himself up by singing the theme song. He is immediately silenced by Peter who tells him to shut up unless he knows a way to get back home.
At Anthrocon 2012, Jim Martin opened up the masquerade event by performing a rebuilt version of Gary Gnu.