| Name | Character | Episodes |
|---|---|---|
| Mary Mouser | Eloise (voice) | 13 |
| Tim Curry | Mr. Salamone (voice) | 13 |
| Rob Paulsen | Bill (voice) | 13 |
| Lynn Redgrave | Nanny (voice) | 13 |
| Phil LaMarr | (voice) | 11 |
| Jeff Bennett | (voice) | 10 |
| Kathleen Gati | Miss Thornton (voice) | 9 |
| Tara Strong | (voice) | 8 |
| Lauren Tom | (voice) | 8 |
| Candi Milo | (voice) | 6 |
| Dionne Quan | (voice) | 5 |
| Brad Garrett | Diamond Jim Johnson (voice) | 4 |
| Matthew Lillard | Monsieur Ducat (voice) | 3 |
| April Winchell | (voice) | 3 |
| Neil Patrick Harris | Philip (voice) | 2 |
| Jim Belushi | Bartolome T. Baxter III (voice) | 2 |
| Doris Roberts | Mrs. Hedwig (voice) | 2 |
| Curtis Armstrong | (voice) | 2 |
| Henry Gibson | Mr. Numblitz (voice) | 2 |
| Kathleen Gati | Miss Thornton (voice; uncredited) | 2 |
| Cynthia Nixon | (voice) | 1 |
| Neil Patrick Harris | (voice) | 1 |
| Lacey Chabert | (voice) | 1 |
| Nestor Carbonell | Diego (voice) | 1 |
| Kevin Michael Richardson | (voice) | 1 |
| Alan Cumming | (voice) | 1 |
| Liliana Mumy | (voice) | 1 |
| April Winchell | Tutor Candidate #3 (voice) | 1 |
| April Winchell | Secretary / Betty's Mom / Janet Palmer (voice) | 1 |
| Tony Jay | (voice) | 1 |
| Jason Marsden | (voice) | 1 |
| Kathleen Gati | (voice) | 1 |