GURPS Shapeshifters contains character creation rules, game environments and sample shifters for various campaign settings.

The first chapter studies the history and mythology of shapeshifters from four periods: the prehistoric, the classical, the medieval and the modern era.

The chapter ends with a discussion of medical conditions that might be involved in "real" lycanthropy: dementia, rabies, porphyria and congenital generalized hypertrichosis.

Included is a sample setting based on British India, where the natives have been granted the ability to turn into bipedal lions by their god so they can repel the invaders.

GURPS Shapeshifters is a 128-page soft-bound book compiled by Robert M. Schroeck and published in 2003 by Steve Jackson Games.