Kerberos, often called Kero, is a guardian beast from the anime series Cardcaptor Sakura. Initially appearing as a small, plush toy-like creature in his sealed form, he reveals his true form as a large, majestic beast resembling a lion with wings. As the guardian of the Clow Cards, Kerberos is tasked with overseeing Sakura's journey as she captures and transforms the cards into Sakura Cards. His playful and sometimes stubborn personality provides comic relief, yet he is fiercely loyal and protective of Sakura.