Beastmen

Beastmen were hybrid-creatures, half-Mortal half-Animal.The Origin of these Beastmen is unknown, some as the ancestors of the Beorning-Shapeshifters were somwetimes thought to descend from Maiar who possessed the ability to transform themselves into mighty Animal-Spirits or Kelfaen.Others however were created by dark sorcerous experiments.

MERP
Examples for Bestmen in MERP include:
 * the Weapons of Amon Lind, Chimaeres created by the Noldo-Magician Elenril
 * Gulthuin, a Dog-Man created by the Sorcery of the Nazgûl Dwâr
 * the Monks of Ereg Eiren, Priests of the Utter South with the ability to shapeshift into large Cats.
 * the high-priestess of Benish Armon who had the ability to transform into a great Cat
 * the Scara-Hai-Orcs, who were able to transform themselves into War-Wolves
 * Were-Rats

The Shapeshifter-Disease was a sorcerous Plight created by the Necromancer of Dol Guldur.Those struck by it would transform themselves into Beasts, for example mannish-Werewolves.