Calvin's Skeleton is a minor alter ego of Calvin's. He appeared in a single weekday strip, where Calvin literally jumped out of his skin to scare his mother with his skeletal appearance.
The dimensions of Calvin's Skeleton were not in line with regular human morphology, but rather with Calvin's cartoonish appearance. However, as he was a fantasy, the skeleton may simply have existed as Calvin imagined it.
See also
- Calvin In Living X-Ray Form