"There are some things you can't share without ending up liking each other, and knocking out a twelve-foot mountain ogre is one of them."
—How facing a mountain ogre made the trio friends
The mountain troll is a breed of Orgre.
They are the largest breed, weighing over a tonne, and the most vicious kind of their species. They are often bald beasts with thick, dark grey skin. They sometimes use Graphorns as mounts, which results in them being scared due to Graphorns heavily disliking such travel.
History
A band of mountain trolls were wreaking havoc in Liechtenstein, which led to Pierre Bonaccord's position as Supreme Mugwump of the International Confederation of Wizards being challenged by the local wizarding community, as he tried to ban ogres-hunting and grant them rights at the time.
A male mountain troll was used as a diversion so that Professor Quirinus Quirrell could attempt to get past Fluffy to capture the Philosopher's Stone for his master, Lord Voldemort.
Late in August 2020, Mountain Ogres rode graphorns through Hungary.