| Name | Character | Episodes |
|---|---|---|
| Deborah Baker Jr. | Sara (voice) | 30 |
| Zosia Mamet | Merian (voice) | 20 |
| Charlyne Yi | Larry (voice) | 20 |
| Gabourey Sidibe | Francis (voice) | 20 |
| Jake Green | Mr. Okay (voice) | 20 |
| Lorraine Toussaint | Dr. Lullah (voice) | 20 |
| Tania Gunadi | Pliny (voice) | 20 |
| Brian Jordan Alvarez | Van (voice) | 1 |
| Parvesh Cheena | Flounder Mutant (voice) | 1 |
| Kaitlyn Robrock | Tara / Baby Tara (voice) | 1 |
| Deborah Baker Jr. | Blobfish Mutant (voice) | 1 |
| Fryda Wolff | Merian's Mom (voice) | 1 |
| Fryda Wolff | Nefarious Plants (voice) | 1 |