Goblin
Part of speech: noun
Definition: A mythical, humanoid creature, often found in contemporary fantasy. A nature spirit in Heathenry.
Gremlin
Part of speech: noun
Definition: A mythical creature reputed to be mechanically inclined and mischievously inclined to damage or dismantle machinery.By extension, any mysterious, unknown source of trouble or mischief.
Example sentence: I remember the first horror movie I saw - I was five years old; it was a direct-to-video movie called 'Truth or Dare: a Critical Madness,' which is sort of badly fantastic or fantastically bad. And then 'Gremlins' was an early movie that I saw, and 'Nightmare on Elm Street 3.'