Peter Pan's shadow is the living shadow of Peter Pan
In the film, while Peter was visiting the Darling household to listen to stories, the Darling's dog Nana barked at the intruders and while Peter escaped, his shadow was captured. That night, Wendy Darling discovered the shadow and stored it in her draw to prevent it from getting into trouble. The next night, Peter and Tinker Bell returned to retrieve it. When they found it, they accidentally woke Wendy. As Peter attempted to restore it with soap, Wendy preferred the proper way, and sewed it back.
Peter Pan's shadow is first shown when Peter Pan send your avatar on a mission to find it. It is like a meet-and-greet character except you must copy his movements and find it three times throughout Disneyland.
In this show, the Shadow is a demonic entity that resides within Neverland and monitors those who exist within it. When a man named Malcolm chooses to stay in Neverland, he gives up his son to the Shadow to retain his youth, and becomes Peter Pan in doing so. The Shadow then becomes Pan's servant, but warns its new master of that Pan's immortality is limited, and will die when his time runs out. Motivated to have companions, Pan orders it to begin bringing children to Neverland.
In London years later, Wendy Darling meets the Shadow outside her nursery window, and it takes her to Neverland. However, after returning from a visit, Wendy reveals that the Shadow now wants one of her brothers, John and Michael to take back with it. To make sure it doesn't succeed, Wendy, John, Michael, and their friend Baelfire hide the next night when the Shadow comes back. However, Michael gets distracted by the Shadow, forcing Baelfire to dash out and have the shadow take him instead of the Darling children. The Shadow accepts the offer, and takes Baelfire towards Neverland. During the flight however, Baelfire lights a match to ward off the Shadow, causing it to drop him into the sea, and after searching for a brief moment, it cannot find Baelfire and flies back to Neverland.
The Shadow appears in present day aiding the Lost Boys in acquiring Henry Mills from the rogue Greg and Tamara. It assists in the attack by stealing Greg's shadow, leaving him in a comatose state, and flies off with its captive. It also appears to Rumplestiltskin as Belle to gain his trust until it is exposed by Regina.
In the Dark Hollow, the Shadow ambushes Emma, Hook and Neal with two other duplicates of himself. Emma is able to capture it however in a candle, and it is then used to allow the Jolly Roger flight to sail the group home. After the ship enters Storybrooke, the creature remains trapped in the sail, as Pan is incapable of controlling it since he himself is imprisoned. Unbeknownst to everyone else, Pan previously switched bodies with Henry. While Pan is inhabiting the body of Henry, he releases the Shadow from the sail, where it then steals the shadow of Mother Superior the following morning.
During the night, the Shadow overhears a plan the residents of Storybrooke have to switch back Henry and Pan to their respective bodies. Upon learning David, Hook, Neal and Tinker Bell are going to procure the Black Fairy's wand for the task, he follows them to a church and attacks. He knocks Hook off his feet, but is captured when Tinker Bell lights a flame on a coconut to draw it in, and proceeds to throw it into an open fire, killing the Shadow and returning Mother Superior's shadow to her body.
Peter's shadow can be seen flying through the walls in the popular dark ride attraction Peter Pan's Flight. The shadow plays a significant role in Disneyland Paris' nighttime show Disney Dreams!. Here, the shadow unleashes some of the magic from The Second Star to the Right. As the shadow enjoys himself with some of the Disney characters, he is attacked by Captain Hook and his Disney Villain allies. Peter and Tinker Bell arrive and successfully restores the magic, defeating Hook.