Trickmaster

The Trickmaster is a minor villain in the Kingdom Hearts Series, including the original Kingdom Hearts, Kingdom Hearts: Chain of Memories, and Kingdom Hearts coded. It's a Heartless that resides in Wonderland.

Kingdom Hearts
Throughout most of  Sora's travel in Wonderland, the Trickmaster is referred to as the shadows or the darkness especially by the Chersire Cat.

After defeating a small army of the Queen of Hearts' Card Guards, Sora and his friends are shocked to find out that Alice has gone missing. They rush off to find her, searching all throughout Wonderland. Eventrually, Sora ended up back to the normal Bizarre Room. The sneaky Cheshire Cat appears and directs Sora's attention to the roof of the room, from which the Trickmaster appears. The Trickmaster drops down from the roof, and attacks Sora and his friends. After a long battle, The Trickmaster was defeated. Once the Heartless has been defeated, Sora discovers Wonderland's keyhole and manages to seal the keyhole.

Kingdom Hearts: Chain of Memories
The Trickmaster was seen in Castle Oblivion as a figment of Sora's memory in his memories of Wonderland. It was revealed that the Trickmaster the one who stole the Queen's memory, which caused her to accuses Alice of this crime. After escaping from the Queen with Alice, Sora battles the Trickmaster, and defeats the creature of darkness.

The Trickmaster also reappeared in front of Riku, as a figment of his memory and was a representation of the darkness within him.

Kingdom Hearts coded
The Trickmaster is the one responsible for the Bug Blox in the Data-Wonderland. It also stole the memories of all the living beings in Data-Wonderland.