The Monstrous Mayhem of the Massive Melviathan is the 31st episode of The Epic Tales of Captain Underpants.
Mr. Krupp makes the kids do arts and crafts so he can sell for the worth of the LeisureMyLand. However, an anomaly in their creations sends them into the Dream Dimension Where Dreams Are Reality, and Melvin tricks Harold into dreaming up their worst nightmare, Melviathan.
- Other Sophie's voice is heard yelling and screaming when she finds a giant bird in the forest, even though Jessica made up a rule that Sophies aren't allowed to talk, which was mentioned in The Abysmal Altercation of the Abominable Altitooth.
- Melviathan is based on the Kraken.
- This is the second episode where the Original Mr. Krupp did not turn into Captain Underpants
- MORAL; without bad there isn’t any bad.