In Paper Mario: The Thousand-Year Door, Koopley is Koops' father. Ever since he came to Hooktail Castle to slay Hooktail, Hooktail swallowed him whole. Koops thought he was dead and joined Mario's team to avenge his death. After Mario, Goombella and Koops defeat Hooktail, Koopley came out of Hooktail's stomach with the first Crystal Star, the Diamond Star.