[Gothmog]

This might be too easy, but anyway... They were all "special" creatures except for poor old Bill. Obviously Huan had special powers, a vala´s pet before he followed Celegorm. Tefildo was altered by Morgoth to grow much bigger and dangerous than an ordinary cat and Thorondor was one of the Great Eagle, large enough to carry a man without problems. But Bill, well he´s just a ordinary pony...