Spinel Sun (スピネル・サン, Supineru San) is the cat-like magical guardian created by Eriol Hiiragizawa as a counter part to Clow Reed's original guardian Cerberus. Spinel Sun's true form is a winged black panther, while his false form is similar to a small winged cat. Nicknamed Suppi by Ruby Moon, Spinel Sun spends most of his time reading and projects a calm demeanor. Ruby Moon often teases him that he needs to have more fun. During the series, he mostly remains out of site of the main characters, except when he once runs into Cerberus in his false form. Fortunately for him, Cerberus doesn't suspect anything and instead declares him a monster and feeds him sweets, not realizing that the sweets would turn Spinel Sun into a hyperactive eating machine. Cerberus does not learn his true identity until just before the final battle where the two cats face one another. Initially, Spinel Sun appears to have the upper hand, however Cerberus' greater determination to protect Sakura enable him to defeat him.
In the anime adaptation, he voiced by Katsuyuki Konishi in his true form, and by Yumi Tōma in his false form. In the second Cardcaptor Sakura movie, his false form briefly appears and is voiced by Philece Sampler. In the English adaptation Cardcaptors, his name is changed to Spinner Sun and both forms are voiced by Colin Murdock.