The Shadow Card has the ability to manipulate and locate other people through their shadows. It can power itself up by collecting the shadows of people and things, but these can be removed if The Shadow is exposed to a bright light source. According to Cerberus, "(The Shadow) can touch us, but we can't touch it". The true form of Shadow looks like an ominous, black, cloaked figure with the hood drawn up, a possible reference to the stereotypical Grim Reaper/Death. It is under The Light, presumably because a light source is required for the casting of shadows.
The Shadow first appeared in Episode 2. Shadow was piling up desks and chairs from Sakura's school outside, possibly as a sort of challenge to the new Cardcaptor. Sakura, who was reluctant at first due to her fear of ghosts, Kero, and Tomoyo revist the school at night to capture the Clow Card. It made itself into a giant monster with the shadows of the surrounding area when Sakura tried to capture it. Tomoyo and Kero help by weakening it with the floodlights around the field, leaving it to Sakura to capture it. In Volume 2 of the manga, it started with attacking a sweets shop Sakura's brother worked at by overturning the shelves, then piling up chairs and desks. When Sakura saw that Syaoran's lightning charm was effective against it, she used The Thunder the same way and weakened it so she could pin it with The Sword.
In Episode 25, it was revealed through Sakura's fortunetelling that Shadow originally appeared in front of Sakura since it wanted to test her. In Episode 7, Sakura used Shadow to capture The Silent by extending the shadow of her sealing wand and making it act like a proxy to the original thing so she was able to catch it without making any noise. Sakura used The Shadow again to catch The Thunder (only in the anime) in Episode 8 in a cage so Syaoran could help weaken it. Finally, it helped catch The Mist in Episode 14 by containing the mist Mist was making.
The Shadow was transformed in Episode 59. During one of Eriol's trials, he trapped Sakura, Tomoyo, and Syaoran in their school while the space inside of it was warped so that every door led to a different room than normal. When Sakura was separated from Tomoyo, she heard Tomoyo singing and used Shadow to "track down the singer's voice".
- The Shadow and The Thunder switch roles in the manga and anime:
- In the manga: The Thunder was used to weaken Shadow
- In the anime: The Shadow was used to ensnare Thunder