Here's some descriptions:
The Extremes
Four cartoon-like characters with big hands, long arms, and Fraggle-like legs and feet. All four are wearing what looks like fuchsia tuxes.
The Purple Extreme is lavendar, with a flat head, a very big (and detailed) mouth, teeth, bulging eyes, and what looks like silver rocks on her head, plus several silver antennae.
The Yellow Extreme has a smaller mouth than the P.E., and a slightly slimmer head, and has an upper row of teeth, vertically-oval glasses (fuchsia, with the eyes in them), and spiky gray hair.
The Orange Extreme has a turned-down shout, baggy bulgy eyes, frizzy orange hair, and teeth on both jaws.
The Blue Extreme is the chubbiest of the group, with a double-chin, bulgy eyes, upper/lower teeth, and two horn-like projections with blue fur at the end of each.
Codzilla
Looks a bit like a lime green Godzilla, but his head looks like a fish's, with big lips, menacing yellow eyes, and a fin at the top. His body looks like a green, scaly Grover, with muscular arms, and a yellowish belly. He also has a tail.
Marty the Earthling (Chris Langham)
Chris is wearing a grayish-silver tux with long black lapels that reach to the navel. He also wears a marroon cummerbund.
Joe Beth GarfToohoo
A fuzzy brown creature in a bikini and tiara. She has an oval-shaped head, fuzzy feathers on her head and shoulders. Her eyes are round and baggy, with yellow eyes and slanted pupils. She has a huge mouth with orange lips, and several teeth (with two lower fangs), and a tongue that hangs out.
Zsa Zsa Porkmustard
A bunch of brown pieces of foam put together, with beady eyes and pink lips. She has several tinsel-like pieces on her.
Amanda
A blond girl.
Bootsie
She has blond hair (very much like Barbie's), and her eyes somewhat "bug out". She has an obvious overbite.
Brad
He has sculpted brown hair, a visible overbite, and wears a sweater.
The Space Lobsters
Basically a group of lobsters (like the Lobster Banditos).
Lobster Debbie
A lobster with red hair and (I think) earrings.
Timrek the Gorf, Oznog, Noel, Tigid
All of the Teppums look like their counterparts, but are wearing vaudevillian outfits, with Christmas bows on their straw hats.
The Orange Fish
Basically an orange fish, with stripes, and flat, hemispherical eyes.
Merlin's Assistant
A peach, pointy-nosed Whatnot with long, curly hair, and dressed as a damsel.
Scurvy
Gonzo dressed as a pirate, with a tri-corner hat and red/black striped shirt.
Jacques Roach
Has sleepy, baggy, hemispherical yellow eyes, long antenna, dirty chef's hat, neckerchief, apron, a cigarrette in his mouth, and a thin moustache and beard. (When he appears on JHAS as Yves, his cigarette and facial hair are removed.)
The Sheep
A white sheep with eyelids.
The Sea Creatures
Muppet clams, octopuses, fish, etc.
Rhonda
A peach Whatnot with curly blond hair, black/gold striped dress, necklace, sleepy teal eyelids, roundish small nose, and big red lips.
The Nylons
Shouldn't be counted. They are guest stars:
http://www.thenylons.com/default.asp
Monster Telethon: Host, Blue, Pink and Purple Monsters
I believe that all of them have appeared on TMS:
Monsterthon Host--a green version of Boppity, with a yellow-orange snout. His eyebrows are slightly "angrier" than Boppity's.
Blue Monster--alias "Dark Green Hunchback Frackle". He's a dark blue-green Frackle, and has a beak, six fangs, black eyebrows, and a muscular build.
Purple Monster--I refer to him as the "Elderly Frackle". He has a furry purple body, and brown three-fingered claws. His brown head is shaped like Boppity's, without the ears and fur. He has a pink mouth w/red tongue, black/white eyebrows, and thinning gray hair.
The Timecaster
A blue vertically-oval headed Whatnot with brown hair, a loud plaid suit, pink eyelids, and a pointy nose.
The Soap Opera: The Baby, The Husband, and The Wife
The Husband--a tall-headed tan Whatnot with yellowish hair, eyebrows, and moustache (no eyes). He has a long slim nose, and a brown suit.
The Wife--a purplish-pink Whatnot with curly white hair, a "drawbridge" mouth with small red lips, pink nose, earrings, and very sleepy eyelids. She wears a yellowish gown with a red sweater.
The Baby--wears a white bonnet, blue shirt, and white bib.
The Story of the Hat-Sharpening King: The Customer
Probably shouldn't be counted; she has a very small part in the script, and she's the "Ted" Muppet with a princess's hat. She could be counted with the rest of the villagers.
The Story of the Hat-Sharpening King: The King
A chubby green creature with pink horn-like things on his head. His eyes look like two fat worms with the white part and pupils showing. His bottom jaw is large, and is yellow with many wrinkles. He also has two bottom fangs. He has a big white moustache and a tuft of hair at the top of his head. In the story, he wore a red vest and white shirt.
The Story of the Hat-Sharpening King: The Stranger (Chris Langham)
He's dressed as a German soldier.
The All Dog Network Announcer
A yellow dog with a large snout and black/blue nose. He has baggy eyes, white hair, glasses, and a few lower teeth. He wore a brown suit.
Ace Yu
A brown dog with pointy ears, and angry eyes. He usually wears a red cap (not sure what kind I could call it), and gray suit. Under his hat he wears a pink bow.
Quackers, Ace Yu's toy duckie
A yellow duck in a sailor's suit.
Bubba the Bartender
The Irish Wolfhound puppet with some brown spots, taxidermist eyes, and dressed in a white shirt and black vest. He also has a few small teeth.
Bugsy Them
A white(mainly), brown, and black bulldog chewing a cigar, and wearing a black hat and brown/black pinstripe suit.
Miss Belle
A lavendar poodle with a pillbox hat. I don't remember what exactly her clothes looked like.
Scruffy
A dark grey dog with a fuzzy muzzle, wearing a black hat and grey/black pinstripe suit.
Mad Dog
A brown dog with a baggy face and muzzle, with a light brown nose. He has a tongue that slightly sticks out, and wearing a brown suit and black hat.
Laughing Boy
A foxhound wearing a black hat and pinstripe suit.
Mac the Dog Waiter
A white terrier with black spots, wearing a white shirt/black vest.
Rusty
A brown dog with glasses.
Colleen Barker
A collie with a pink pillbox hat and dress. (I think; I'm not sure)
The Graffiti Guys: Blue Guy, Purple Guy, Girl, and Dog
Pink Guy--very thin; very "foam-looking", with a large overbite, blue triangular sunglasses, and four pink spikes on his head.
Blue Guy--has a big chin, wide eyes, and a triangular body. I can't remember him well.
Green Girl--has no eyes, (?)-colored pigtails, and a red/yellow zigzag body.
Orange Dog--has a zigzag-shaped muzzle (near the mouth), red nose, and jagged ears. He has no legs, but he does have feet.
Anthony Rudd
Looks sort of like a cockroach, but with the face similar to an onion. He wore a grey/brown suit, glasses, and small eyes, and curled antenna.
Fern Rudd
Looks like "the Creature from the Black Lagoon", with what looks like circular holes in the top of her head, exposing a "brain". She has a rim of green feathers around the back and sides of her head. She has large yellow eyes, sleepy pink eyelids, and large pink lips.
Bruno, Anthony and Fern Rudd's pet tarantula
Looks like the TMS tarantula, but the performer's head is the performer's head. It looks like the legs are stilts. Also, he has angry yellow eyes.
Chip
An oval-headed peach whatnot with a patch of brown curly hear at the top of his head. He wears a checkered jacket, red glasses, and has lidless eyes (with pupils that blink). He has an upper row of teeth.
(NOTE: He is also known as Lester Z'Dwango on MT.)
Ubu
An orange creature with a gorilla-like face, moving brows, lots of feathery blue hair, with some in a pigtail (at the top of his head). He wore a colorful shirt and vest.
Zondra
Has peach skin, oval head, fuzzy black hair, black eyelids, slender nose, and is very skinny. He wears a black dress, her hands and arms look as if they're wrapped in black tape. She has pins for earrings.
The Ultra-Gorgon
A very, VERY large half-made creature. He has wings, and his head is a purplish-brown color, with a turned-down snout. I think he had gills.
I'll tell you more later. I've gotta rest my wrists!