Koopley is a character that first appeared in the game Paper Mario: The Thousand-Year Door for the GameCube. His species is a Koopa Troopa. In the game, the residents of Petalburg thought that Hooktail ate Koopley on the account that he never returned on his adventure to slay the beast. So Koopley's son, Koops, decides to be a partner with Mario so that he can go avenge his father, and to show that he's brave to the residents of the town. Once the duo enter Hooktail's lair and defeat Hooktail, Koopley will pop out of her mouth alive, with the Crystal Star that Mario is been looking for. Koopley then gives the star to Mario, thanking him for keeping his son safe, and for saving him.
Koopley was stuck in Hooktail's stomach for over 10 years hiding in his shell. Like most Koopa Troopas, his name starts with a Koop. During Mario's quest, Koopley will send you e-mails via the SP-Mail.
The Koopa Troopa has a blue shell, unlike his son's natural green shell. Koopley also has shoes that match his shell, and has big eyebrows and a beard.