
| Olivia Hack | ... | Rhonda Wellington Lloyd (40 episodes, 1996-2002) |

| Toran Caudell | ... | Arnold / ... (32 episodes, 1996-2001) |

| Phillip Van Dyke | ... | Arnold / ... (31 episodes, 1997-2000) |
 | Spencer Klein | ... | Arnold (III) (27 episodes, 1999-2002) |
 | Francesca Smith | ... | Helga Pataki / ... (24 episodes, 1996-2000) |
 | Craig Bartlett | ... | Brainy / ... (8 episodes, 1996-2003) |

| Jamil Walker Smith | ... | Gerald Martin Johanssen / ... (7 episodes, 1996-1998) |
 | Danica Ivancevic | ... | Hospitalized Woman / ... (7 episodes, 1996-2000) |
 | Christopher Walberg | ... | Stinky Petersen / ... (6 episodes, 1996-1997) |
 | Sam Gifaldi | ... | Sid (5 episodes, 1996-1997) |

| Dan Castellaneta | ... | Additional Voices / ... (5 episodes, 1996-1997) |
 | Kath Soucie | ... | Miriam Pataki / ... (5 episodes, 1996-1998) |
 | Carlos Alazraqui | ... | Carlos / ... (5 episodes, 1996-2002) |

| John Mariano | ... | Morrie / ... (5 episodes, 1996-2002) |
 | Avriel Epps | ... | Timberly (5 episodes, 1996-1999) |

| Marcus Toji | ... | Park / ... (5 episodes, 1996-1998) |

| Lori Alan | ... | Brooke Lloyd / ... (5 episodes, 1997-2001) |
 | Anndi McAfee | ... | Phoebe Heyerdahl / ... (4 episodes, 1997-1998) |

| Justin Shenkarow | ... | Harold / ... (4 episodes, 1996-1997) |

| Lisa Fuson | ... | Danny's Mother / ... (4 episodes, 1996-2000) |

| James Belushi | ... | Coach Wittenberg (4 episodes, 1996-1999) |

| Tony Jay | ... | Rex Smythe-Higgins / ... (4 episodes, 1996-1999) |
 | Michael Bacall | ... | Torvald / ... (4 episodes, 1996-1997) |
 | Joey Paul | ... | Mindy / ... (4 episodes, 1996-1997) |
 | Tress MacNeille | ... | Additional Voices / ... (3 episodes, 1996-1997) |
 | Steve Viksten | ... | Oskar Kokosha / ... (3 episodes, 1996-1998) |
 | Dom Irrera | ... | Ernie Potts / ... (3 episodes, 1996-1997) |
 | David Wohl | ... | Jerry Berman / ... (3 episodes, 1997) |
 | Baoan Coleman | ... | Mr. Hyunh (3 episodes, 1996-1998) |
 | Mary Scheer | ... | Suzie Kokoshka (3 episodes, 1997-1998) |
 | Lou Rawls | ... | Harvey (3 episodes, 1996-1999) |

| Maurice LaMarche | ... | 'Big' Bob Pataki / ... (3 episodes, 1996-1998) |
 | Jarrett Lennon | ... | Eugene / ... (3 episodes, 1996-1997) |
 | Rick Corso | ... | Dino Spumoni (3 episodes, 1996-1999) |

| Shari Belafonte | ... | Mrs. Johanssen (3 episodes, 1996-1997) |
 | Mary Gross | ... | School Nurse Shelley (3 episodes, 1997-2002) |
 | Sam McMurray | ... | Buckley Lloyd / ... (3 episodes, 1997-2001) |
 | Cathy Moriarty | ... | Tish Wittenberg (3 episodes, 1997-1999) |

| Maria Bamford | ... | Mayor Dixie / ... (3 episodes, 1998-1999) |
 | Dan Butler | ... | Mr. Simmons (2 episodes, 1997) |
 | Ben Diskin | ... | Eugene Horowitz / ... (2 episodes, 1997-2000) |
 | Rick Fitts | ... | Martin Johanssen / ... (2 episodes, 1997) |
 | Ashley Buccille | ... | Lila Sawyer (2 episodes, 1997-1998) |

| Kathy Najimy | ... | Madame Blanche (2 episodes, 1997-1999) |

| Mayim Bialik | ... | Maria (2 episodes, 1996-1999) |
 | Pamela Hayden | ... | Connie (2 episodes, 1996-1999) |

| Ron Perlman | ... | Mickey Kaline / ... (2 episodes, 1996-1998) |
 | Elizabeth Ashley | ... | Mrs. Vitello (2 episodes, 1996-1997) |
 | Billy Riback | ... | Announcer / ... (2 episodes, 1996-1997) |
 | Caroline Aaron | ... | Landlady / ... (2 episodes, 1996) |
 | Frank Martorana | ... | Burt / ... (2 episodes, 1996) |

| Vincent Schiavelli | ... | Mr. Bailey / ... (2 episodes, 1996) |

| Harvey Korman | ... | Don Reynolds (2 episodes, 1997-1999) |
 | John Rubano | ... | Doctor / ... (2 episodes, 1997-1999) |
 | Lloyd Sherr | ... | Tape Voice / ... (2 episodes, 1997-1999) |

| Elliott Gould | ... | Rabbi Goldberg (2 episodes, 1997-1998) |
 | Joey Stinson | ... | Rex Smythe-Higgins III (2 episodes, 1997-1998) |

| Lacey Chabert | ... | Ruth P. McDougal (2 episodes, 1997) |

| Joseph Ashton | ... | Iggy (2 episodes, 1998-2002) |
 | Gregg Berger | ... | Amusement Park Worker / ... (2 episodes, 1998) |

| Victor Lopez | ... | Lorenzo (2 episodes, 1998) |

| Bronson Pinchot | ... | Chauffeur / ... (2 episodes, 1998) |
 | Joe Lala | ... | Miller / ... (2 episodes, 1999-2002) |
 | Cameron Van Hoy | ... | 'Big' Gino (2 episodes, 1999-2002) |
 | Grant Hoover | ... | Arnie (2 episodes, 1999-2001) |
 | Michael Levin | ... | Dino Spumoni / ... (2 episodes, 1999) |

| Laraine Newman | ... | Kid With Map / ... (2 episodes, 1999) |
 | Antoinette Stella | ... | Arnold's Mother / ... (2 episodes, 2000-2002) |

| Alex D. Linz | ... | Arnold (2 episodes, 2002) |
|
 | Christopher Castile | ... | Eugene Horowitz (I) (unknown episodes, 1996) |
 | Blake McIver Ewing | ... | Eugene Horowitz (IV) (unknown episodes, 2001) |
 | Nika Futterman | ... | Olga Pataki (unknown episodes) |
 | Jordan Warkol | ... | Chocolate Boy (unknown episodes) |
|
| Jay Lender | .... | storyboard artist (11 episodes, 1997-1999) |
| Clint Bond Jr. | .... | prop designer (5 episodes, 1996-1998) |
| Miyuki Hoshikawa | .... | assistant storyboard artist (5 episodes, 1996-1998) |
| Tim Parsons | .... | assistant storyboard artist / storyboard artist: Harold's Kitty / ... (4 episodes, 1997-2004) |
| Stark Howell | .... | storyboard director / storyboard director: The Big Scoop (3 episodes, 1996-1998) |
| Chris Robertson | .... | assistant storyboard artist / storyboard artist (3 episodes, 1996-1998) |
| Sherm Cohen | .... | assistant storyboard artist / storyboard artist (3 episodes, 1996-1997) |
| Carson Kugler | .... | assistant storyboard artist (3 episodes, 1997-1998) |
| Steve Lowtwait | .... | assistant storyboard artist (3 episodes, 1997-1998) |
| Ted Seko | .... | assistant storyboard artist (3 episodes, 1997-1998) |
| Claudia Stegall | .... | prop designer (3 episodes, 1997-1998) |
| Tricia Garcia | .... | storyboard artist / storyboard director: Harold's Kitty (2 episodes, 1996-1997) |
| Tuck Tucker | .... | storyboard director (2 episodes, 1996-1997) |
| Melissa Suber | .... | assistant storyboard artist (2 episodes, 1996) |
| Amber Tornquist | .... | assistant storyboard artist (2 episodes, 1996) |
|
| Debbie Baber | .... | storyboard artist (unknown episodes) |
| Aldin Baroza | .... | assistant storyboard artist (unknown episodes) |
| Paul Finn | .... | animatic (unknown episodes) |
| John Flagg | .... | storyboard artist (unknown episodes) |
| Louis Gallegos | .... | assistant storyboard artist (unknown episodes) |
| Kevin Kirwan | .... | colorist: DaVinci (unknown episodes) |
| Edgar Larrazábal | .... | assistant storyboard artist (unknown episodes) |
| Caesar Martinez | .... | assistant storyboard artist (unknown episodes) |
| Vanessa J. Martin | .... | property designer (unknown episodes) |
| Jerilyn Mettlin | .... | animatic (unknown episodes) |
| Stephen Sandoval | .... | storyboard artist (unknown episodes) |
| Catherine Simmonds | .... | color key stylist (unknown episodes) |
| Karin Stover | .... | painter (unknown episodes) |
| Erik Wiese | .... | storyboard artist (unknown episodes) |
| |
|
| Jay Lender | .... | storyboard artist / layout designer (6 episodes, 1996-1998) |
| Doug Appleton | .... | background painter (5 episodes, 1996-1998) |
| Craig Bartlett | .... | original character designer / character designer (5 episodes, 1996-1998) |
| Clint Bond Jr. | .... | character designer (5 episodes, 1996-1998) |
| Al Budnick | .... | background painter (5 episodes, 1996-1998) |
| Christine Kolosov | .... | animatic coordinator / background coordinator / ... (5 episodes, 1996-1998) |
| Larry Leichliter | .... | animation director / sheet timer / ... (5 episodes, 1996-1998) |
| Caesar Martinez | .... | layout designer (5 episodes, 1996-1998) |
| Kenji Notani | .... | background painter (5 episodes, 1996-1998) |
| Steve Socki | .... | animation director / animation director: Harold's Kitty / ... (4 episodes, 1996-1998) |
| Paul Finn | .... | animatic (4 episodes, 1996-1997) |
| Brian Mark | .... | layout designer / layout supervisor (4 episodes, 1996-1997) |
| Karin Stover | .... | ink artist / painter / ... (4 episodes, 1996-1997) |
| Teale Wang | .... | color key supervisor (4 episodes, 1996-1997) |
| Catherine Simmonds | .... | color key stylist (3 episodes, 1996-1997) |
| Hugh MacDonald | .... | layout designer (3 episodes, 1997-1998) |
| Claudia Stegall | .... | character designer (3 episodes, 1997-1998) |
| Adriana M. Galvez | .... | background painter (2 episodes, 1996) |
| Nick Jennings | .... | background painter (2 episodes, 1996) |
| Steve Lowtwait | .... | layout designer (2 episodes, 1996) |
| Skinny Wen | .... | overseas animation supervisor (2 episodes, 1996) |
| George S. Chialtas | .... | sheet timer (2 episodes, 1997) |
| Jerilyn Mettlin | .... | animatic (2 episodes, 1997) |
| Karen Shaffer | .... | final checker (2 episodes, 1997) |
|
| Charles Garcia | .... | clean-up artist (unknown episodes) |
| Don Judge | .... | animation director (unknown episodes) |
| Jamie Mitchell | .... | sheet timer (unknown episodes) |
| Russ Mooney | .... | animation director (unknown episodes) |
| Howy Parkins | .... | animation director (unknown episodes) |
| Alan Smart | .... | animation director (unknown episodes) |
| Frank Weiss | .... | animation director / directing animator (unknown episodes) |
| |
|
| Robert Cseko | .... | financial services / financial services: Nickelodeon (4 episodes, 1996-1997) |
| Jonathon E. Goley | .... | overseas supervisor / overseas background supervisor (4 episodes, 1996-1997) |
| Bill Hutten | .... | financial services / financial services: Nickelodeon (4 episodes, 1996-1997) |
| Danica Ivancevic | .... | assistant to writers (4 episodes, 1996-1997) |
| Jim Lara | .... | production assistant / production coordinator (4 episodes, 1996-1997) |
| Larry Leichliter | .... | supervising director (3 episodes, 1997-1998) |
| Steve Socki | .... | supervising director (3 episodes, 1997-1998) |
| Lisa Fuson | .... | assistant to producers / executive assistant (2 episodes, 1996-1997) |
| Vince Calandra | .... | story editor: Nickelodeon (2 episodes, 1996) |
| Lora Lee | .... | story editor: Nickelodeon (2 episodes, 1997-2003) |
| Vito Curcuru | .... | production assistant (2 episodes, 1997) |
| Jonathan Greenberg | .... | story editor (2 episodes, 1997) |
| Stephanie Henning | .... | intern (2 episodes, 1997) |
| Kristina Klockars | .... | executive assistant (2 episodes, 1997) |
| Michelle Lamoreaux | .... | executive assistant (2 episodes, 1997) |
| Ryan Slater | .... | production coordinator (2 episodes, 1997) |
| Dave Warden | .... | production assistant (2 episodes, 1997) |
|
| Heather Morgan | .... | publicist (unknown episodes, 2003) |
| Joe Ansolabehere | .... | developer (unknown episodes) |
| Craig Bartlett | .... | developer / original characters / ... (unknown episodes) |
| Christie Insley | .... | executive assistant (unknown episodes) |
| Romney T. Marino | .... | production intern (unknown episodes) |
| Ani Martirossians | .... | production assistant (unknown episodes) |
| Jamie Mitchell | .... | supervising director (unknown episodes) |
| Tuck Tucker | .... | supervising director (unknown episodes) |
| Mark Valenti | .... | story editor (unknown episodes) |
| Steve Viksten | .... | developer (unknown episodes) |
| |