| Name | Character | Episodes |
|---|---|---|
| Wendie Malick | Mrs. X (voice) | 20 |
| Patrick Warburton | Mr. X (voice) | 20 |
| Lynsey Bartilson | Tuesday X (voice) | 20 |
| Chris Hardwick | Glowface (voice) | 20 |
| Jansen Panettiere | Truman X (voice) | 20 |
| Tom Kane | 4 | |
| Randy Poffo | 3 | |
| Stephen Root | 2 | |
| Dee Bradley Baker | 2 | |
| Tom Kenny | 2 | |
| Ashley Johnson | 1 | |
| Jason Schwartzman | 1 | |
| Lindsay Sloane | 1 | |
| Laura Marano | Andrea (voice) | 1 |
| Laura Marano | Scout Y (voice) | 1 |
| Soleil Moon Frye | 1 | |
| Chris Hardwick | 1 |