It's not easy being a teen like Duncan. His mom wants him to pay more attention to his homework, while his dad - a 120-foot-tall monster known as a Kaiju - wants him to become the next King of All Monsters. When these worlds collide, Duncan must use his human wits and his Kaiju powers - including super strength, agility and the ability to breathe fire - to protect his family and friends from a giant monster rampage.
| Actor | Role |
|---|---|
 Dana DelanyMargaret Rosenblatt (voice) | Margaret Rosenblatt (voice) |
 Jesse HeadDuncan Rosenblatt (voice) | Duncan Rosenblatt (voice) |
 Dante BascoKenny Rogers (voice) | Kenny Rogers (voice) |
 Grey DeLisleMs. Dreakford (voice) | Ms. Dreakford (voice) |
 Reed DiamondBarnes (voice) | Barnes (voice) |
| BBilly EvansSteve (voice) | Steve (voice) |
 Josh KeatonTroy (voice) | Troy (voice) |
| JJameson MossBig Rob (voice) | Big Rob (voice) |
 Kevin Michael RichardsonBelloc (voice) | Belloc (voice) |
 Nicole SullivanDr. Pytel (voice) | Dr. Pytel (voice) |
| TTom TartamellaWhitey (voice) | Whitey (voice) |
 Tia TexadaIsabel (voice) | Isabel (voice) |
 Gary Anthony WilliamsPrincipal Dave / Troy's Dad (voice) | Principal Dave / Troy's Dad (voice) |
 Amy DavidsonJenna (voice) | Jenna (voice) |
 Frank WelkerDragon 1 (voice, uncredited) | Dragon 1 (voice, uncredited) |