 Jolie Hoang-RappaportStevie (voice) | Stevie (voice) |
 Elias JanssenElliot (voice) | Elliot (voice) |
 Simu LiuDad (voice) | Dad (voice) |
 Craig RobinsonBaloney Tony (voice) | Baloney Tony (voice) |
 Cristin MiliotiMom / Additional Voices (voice) | Mom / Additional Voices (voice) |
 Gia CaridesNightmara (voice) | Nightmara (voice) |
 Omid DjaliliSandman (voice) | Sandman (voice) |
 SungWon ChoChad / Additional Voices (voice) | Chad / Additional Voices (voice) |
 Zachary Noah PiserJoon Bae / Polly (voice) | Joon Bae / Polly (voice) |
| HHailey MagpaliFour-Year-Old Stevie (voice) | Four-Year-Old Stevie (voice) |
| FFrancis BensonFour-Year-Old Elliot (voice) | Four-Year-Old Elliot (voice) |
 Kai ZenEight-Year-Old Stevie (voice) | Eight-Year-Old Stevie (voice) |
 Bob BergenBlue Clown Pacifier / Additional Voices (voice) | Blue Clown Pacifier / Additional Voices (voice) |
| MMaisie BensonCereal Kid (voice) | Cereal Kid (voice) |
 Jorge DiazSausage Dog (voice) | Sausage Dog (voice) |
| QQuinn Minichino EakinsBlueberries (voice) | Blueberries (voice) |
| EErik BensonDelilah (voice) | Delilah (voice) |
 Lizzie FreemanSandling (voice) | Sandling (voice) |
 Kellen GoffSandling / Additional Voices (voice) | Sandling / Additional Voices (voice) |
 Scott MenvilleSandling (voice) | Sandling (voice) |
 Alex CazaresScary Grandma / Additional Voices (voice) | Scary Grandma / Additional Voices (voice) |
| RReese WarrenFriend with Braces (voice) | Friend with Braces (voice) |
 Hunter Clayton DixonAdditional Voices (voice) | Additional Voices (voice) |
 David Errigo Jr.Additional Voices (voice) | Additional Voices (voice) |
 Matthew Yang KingAdditional Voices (voice) | Additional Voices (voice) |
 Tara StrongAdditional Voices (voice) | Additional Voices (voice) |
| MMiriam WallenAdditional Voices (voice) | Additional Voices (voice) |
