When not sketching environments or people, we all also sketched beasts from Borges's The Book of Imaginary Beings. Seeing everyone's different take on a base concept is always fun; it's a great exercise. Here are scans of a couple of mine. Perhaps I'll clean them up a bit and add color / rendering as time permits.
T'AO T'IEH (饕餮),饕餮) is a beast from Chinese mythology, described as having the giant head of a dragon, tiger, or person atop two bodies, with a shared set of forearms. The T'ao-T'ieh was also described as an "ogre-mask", inspired by the "devil of symmetry". It serves as a warning against self-indulgence. (Fitting to have sketched this while in Amsterdam.)