Trolls

Trolls are giant, formidable Magical Creatures known throughout the Wizarding World for their immense strength and equally profound lack of intelligence. Native to Scandinavia and northern Europe, these beasts are often violent and unpredictable. Despite their stupidity, their prodigious power makes them highly sought-after as guardians for powerful magical items or locations. They were also known to have fought alongside Lord Voldemort's forces during the Second Wizarding War.

A fully grown troll can stand up to twelve feet tall and weigh over a tonne. Their bodies are typically lumpy and boulder-like, with disproportionately short, thick legs and long, dangling arms. Their skin colour and features vary between the known subspecies. The Mountain Troll encountered by Harry Potter had dull, granite-grey skin, a small bald head, and flat, horny feet. All trolls possess a notoriously foul stench, often compared to a mixture of old socks and an uncleaned public toilet. There are three known types of troll (Fantastic Beasts and Where to Find Them):

• Mountain Troll: The largest and most vicious type. They are bald with pale-grey skin.
• Forest Troll: These trolls have pale-green skin and may have sparse, hair-like growths that are either green or brown.
• River Troll: Characterised by their purplish skin, River Trolls may have short horns and be hairy. They are known to lurk beneath bridges.

Trolls are considered to have exceptionally low intelligence, ranking them among the less clever magical beasts. They communicate primarily through a series of grunts and roars, though a crude language is believed to exist among them. Some more intelligent specimens can be taught to understand and even speak a few simple human words, making them trainable as guards. Their behaviour is predominantly driven by basic needs and aggression, and they are not known for their sophisticated reasoning. They are omnivorous but have a preference for raw flesh.

Trolls have appeared at several key moments in recent wizarding history, often in a security or combat capacity.

• Hallowe'en Attack (1991): Professor Quirrell, under the influence of Lord Voldemort, let a full-grown Mountain Troll into Hogwarts School of Witchcraft and Wizardry as a diversion. The troll cornered Hermione Granger in a girls' bathroom before being knocked unconscious by Ron Weasley, who used the Levitation Charm (Wingardium Leviosa) to drop its own club on its head. This event was pivotal in cementing the friendship between Harry, Ron, and Hermione.
• Guardian of the Philosopher's Stone: A different troll was one of the magical obstacles guarding the Philosopher's Stone. When the trio reached its chamber, the troll had already been defeated by Professor Quirrell.
• Security Forces: Trolls were employed as security guards by the Ministry of Magic at large events, such as the Quidditch World Cup in 1994.
• Battle of Hogwarts: During the final battle of the Second Wizarding War, an army of trolls fought on the side of the Death Eaters, using their immense strength to smash through the castle's defences.
• Troll By-products: Parts of a troll are used in the magical world. Troll Bogeys are a known Potions ingredient, and Troll Whiskers have been used as a Wand core, although it is considered an inferior substance (Pottermore).

According to the book Fantastic Beasts and Where to Find Them, the Ministry of Magic Department for the Regulation and Control of Magical Creatures gives trolls a classification of XXXX: Dangerous / Requires specialist knowledge / Skilful wizard may handle.

• The primary source for the different troll species and their detailed habits is the in-universe textbook Fantastic Beasts and Where to Find Them, written by Newt Scamander and later published for Muggles.
• In the film adaptation of Harry Potter and the Philosopher's Stone, the troll's appearance is largely faithful to the book's description. Its design became iconic for the film series.
• The painting of Barnabas the Barmy attempting to teach trolls ballet, located near the Room of Requirement, is a recurring visual gag in both the book and the film for Harry Potter and the Order of the Phoenix.
• According to Pottermore, the wand of Sir Cadogan contained a troll whisker. This is said to be a “dubious” core that often makes the owner accident-prone and inept at subtle magic.