The Dancing Skeleton

The Dancing Skeleton is a creature that lives in Shudder Mansion. He appears in the book Escape from Shudder Mansion.

History
In the book, Riley Shiner encounters it when he's in a sort of daydream, and enters Shudder Mansion. The Dancing Skeleton starts dancing a sailor's jig, and Riley watches him too long. The skeleton attacks him, and starts trampling him. Riley wakes up, then to his horror finds two bony fingers gripped tightly in his palm.

Physical appearance
It looked like a normal human skeleton, with a toothless grin and eyeless skull. It had thick spider-webs clinging to its rib-cage.