Background characters

• 
  3rd Grade Male Bear (Number 2)

• 
  Alien (Fernkenstein's Monster)
• 
  Aliens (Buster the Lounge Lizard)
• 
  Aliens (Feeling Flush)
• 
  Aliens (The Boy Who Cried Comet)
• 
  Aliens (The Contest)
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  Alphonse (cat)
• 
  Alyssa
• 
  Amigo's great-grandfather
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  Amigo's great-grandfather's owner
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  Anton
• 
  Arthur lookalike (The Chronicles of Buster)
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  Arthur lookalike (The Perfect Game)
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  Arthur's great-uncle

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  Bacon (The Secret Life of Dogs and Babies)
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  Ballerina (Muffy Goes Metropolitan)
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  Bat Arthur
• Bat D.W.
• 
  Bill (aardvark)
• 
  Bingo roller (Arthur Loses His Marbles)
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  Binky's evil twin
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  Binky's grandmother
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  Bird (Nicked by a Name)
• 
  Bitzi lookalike (Background Blues)
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  Robert Black
• Bob (Cereal)
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  Bob (pool worker)
• 
  Bob (robot)
• 
  Bobo (Do You Believe in Magic?)
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  Bongo
• 
  Bongo Player
• 
  Bowling alley worker
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  Bowser
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  Brain lookalike (Alfred)
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  Brobot
• 
  Buffalo Bill
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  Burmy the Bonecrusher
• 
  Buster lookalike (Alfred)

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  Camel (Is That Kosher?)
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  Capitol tour guide
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  Captain (Titan XII)
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  Captain Nemo
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  Carol
• 
  Caroline
• 
  Cat (The Law of the Jungle Gym)
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  Chelsea
• 
  Vicky Chow
• 
  Cinderella
• 
  Clock (Fifteen)
• 
  Clown Face's henchmen
• 
  Cookie
• 
  David Cossin
• 
  Creepy Cool Mutant Alien
• 
  Crocodile (Nicked by a Name)
• 
  Crouton Creature
• 
  Crush Meister

• 
  Dave (rabbit)
• 
  Deadly Nightshade
• 
  Deeangeleenora Woo
• 
  Dex
• 
  Doctopus
• 
  Dottie
• 
  Doug
• 
  Dr. Night
• 
  Dr. Zimmer
• 
  Drummer (Los Viajeros)
• 
  Drummer (The Ratburn Rats)
• 
  Dwayne Lutz

• 
  Ebos Schachter
• 
  Elephant puppies
• 
  Employer
• 
  Errol
• 
  Essie Beauchamp

• 
  Fenrir
• 
  Ferret Girl
• 
  First mate
• 
  Flex McGinty
• 
  Flippity Frank
• Floyd Peterson
• 
  Francine lookalike (The World of Tomorrow)
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  Francine's aunt's chameleon
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  Francis Haney's dog
• 
  Francis Wheaton
• 
  Frankenstein (character)
• 
  Frumpus

• 
  General Mayhem
• 
  Ghost-doe
• 
  Goldie
• 
  Gondola rower

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  Hal
• 
  Highway patrol
• 
  Herbert Hoover
• 
  Hydrozor

• 
  James' unknown relative (Number 2)
• 
  Thomas Jefferson
• 
  Jenna Morgan
• 
  Julie

• 
  Katie
• 
  Keith Powers
• 
  Ken
• 
  Keyboardist (Los Viajeros)
• 
  Keyboardist (The Ratburn Rats)
• 
  Kindergarten Male Aardvark (Number 2)

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  Larry
• 
  Leonardo da Vinci
• 
  Abraham Lincoln
• 
  Luke's mother

• 
  Manny (chef)
• 
  Megatoad
• 
  Gregor Mendel
• 
  Mime
• 
  Mincey Poodlemeyer
• 
  Moon Hamster
• 
  Mr. McInnerny
• 
  Mr. Morgan
• 
  Mrs. Bickles
• 
  Mrs. Fox
• 
  Mrs. Higgenbottom
• 
  Mrs. Johnson
• 
  Mrs. Lamott
• 
  Mrs. Radley
• 
  Ms. Tremello
• 
  Muffy's hamster
• 
  Multitasker

• 
  Otis' mother

• 
  Paul Desmarais
• 
  Penny (alligator)
• 
  Phil
• 
  Piano Tamer
• 
  Pixel
• 
  Polar Bear
• 
  Pordro
• 
  Priest
• 
  Prudence
• 
  Puk-Puk
• 
  Putty Person

• 
  Unknown Female Rabbit (Number 11)
• 
  Unknown Estabrook Student
• 
  Unknown Female Adult Aardvark (Number 3)
• 
  Unknown Female Adult Rabbit (number 10)
• 
  Unknown Female Rat
• 
  Unknown Male Adult Dog (Number 5)
• 
  Unknown Male Adult Monkey
• 
  Unknown Male Bear (Number 11)
• 
  Unknown Male Cat (Number 3)
• 
  Unnamed female rat girl

• 
  Queen Sapphirella

• 
  Rabbi
• 
  Rafi
• 
  Rat Villain
• 
  Ringo
• 
  Rita Hareworth
• Rob
• 
  RoboCount
• 
  Robots (Arthur Accused!)
• 
  Ron and Don
• 
  Russell

• 
  Sadie (person)
• 
  Sadie (pet)
• 
  Sally (pig)
• 
  Science officer
• 
  Seth's father
• 
  Sirius the Super Dog
• 
  Skunkamunkah
• 
  Sleipnir
• 
  Slip Bumfield
• 
  Speech therapist
• 
  Speedy (gerbil)
• 
  Spot and Dot
• 
  Squid People
• 
  Starry Moony (character)
• 
  Steve
• 
  Mark Stewart
• 
  Strong guy

• 
  Tatsuya Matsumoto
• 
  Terrific Three
• 
  Thora lookalike (The Chronicles of Buster)
• 
  Thora's brother 3
• 
  Thora's mother's great-uncle
• 
  Tibble Cat
• 
  Tibble Cat (Number 2)
• 
  Timber Twins
• 
  Tina Trampolina
• Tiny Tim
• 
  Tiny Tommy Tornado
• 
  Tiny Tornado
• 
  Tom Tapir
• 
  Tomato (Buster's Garden of Grief)
• 
  Top-eye
• 
  Tosca
• 
  Trip
• 
  Tronic
• 
  Tut's mother
• 
  Tyrone Bellows

• 
  Villain (Buster's New Friend)
• 
  Villain (D.W. the Copycat)
• 
  Villain (To Eat or Not to Eat)
• 
  Villain Male Rat
• 
  Villains (Brother, Can You Spare a Clarinet?)
• 
  Vladimir and Estragon