Granny Whitlow

The Light Fantastic briefly mentions a Granny Whitlow, an evil witch who builds a candy cottage and is eventually pushed into an oven by two small children (a la Hansel and Gretel). This seems to be one of those stories that go around the Multiverse in a regular rotation.

Annotation

A whitlow in Roundworld is a septic abscess on the tip of the finger which is often under the nail, and can be supremely painful.