Eborsisk

The Eborsisk is a frightening giant monster and a villainous force in the fantasy film, Willow, the result of the titular hero's attempt to use magic to dispose of a threatening troll - only to have the spell backfire and transform the troll into a far greater threat than it was originally.

Trivia
The Eborsisk is similar in many ways to dragons, hydras and ettin - all of which are feared in fantasy settings as powerful and often malevolent figures capable of taking on small armies by themselves : the Eborsisk is also notable as a monster created (albeit without intention) by the hero of the story.