Troll
From Equestripedia, the Archives of Equestria!
Trolls are a race of semi-humanoid creatures who live all throughout Equestria and the Mysterious South, though the overall features seem to vary on the type of troll.
Behind the scenes
Trolls and goblins were relatively common stock enemies for the ponies to go up against in early My Little Pony media, mainly comics and books. In the first storyline of the IDW Publishing comic series Friendship is Magic, the Mane Six encountered a kind-hearted cave troll named Jim, who was later revealed to be an internationally infamous figure in the Convocation of Creatures storyline.
As seen in The Art of My Little Pony: The Movie, "Slug Trolls" were initially going to appear in the 2017 film but were scrapped.