|Episode name pun on: Monstrosity|
|Airdate:||September 5, 2003|
|Story:||David A. Dunnet|
Amy Keating Rogers
Justin K. Thompson
"Shut the Pup Up"
Monstra-City is the first episode of Season 5.
When the Mayor of Townsville finds the deed to Monster Isle, the Monsters move to Townsville causing havoc between monsters and humans. The Powerpuff Girls try to keep the peace and let everyone in Townsville live in harmony. But when Townsville gets way too crowded, they trick the Mayor into giving back Monster Isle to all of the monsters with the help of a monster lawyer.
- This is the one of the episodes ending with the narrator saying his catchphrase differently: "And so, once again, the day is saved, thanks to the all-binding, all-powerful, all-encompassing legal system!"
- Steven Blum voices the architect. He is the voice of Spike Spiegel from Cowboy Bebop, Green Lantern in Injustice 2, and was voicing TOM (more specifically, TOM 3) on Toonami at this time, and The Powerpuff Girls aired on Fridays during the block until 2005.
- This episode was disliked by the majority because good people and good monsters must be nice to each other, no matter what every time, period.
- This was the first episode produced in 2003 according to the credits.
- This was also the first episode to premiere in 2003.