A Troll is a rock like creature that comes in many sizes, resembling rocks in daylight with long noses, and a large beast in the nighttime. They appear in the graphic novel series, the animated series, and the Hilda Tie-In Series.
In the graphic novels, two different origins for the Trolls as a species are given:
- According to the information about Giants of Old seen in the back of "Hilda and the Midnight Giant", both Nisse and Trolls are descendants of the giant Björg.
- In "Hilda and the Mountain King" however, it is stated that all Trolls (or at least those living in the area of Trolberg) are the children of Amma. This theory is also brought up in the movie adaptation
It is possible that Amma was the only child of Bjorg, thus rendering both theories true.
The tie-in novels so far have not given any information regarding the history of trolls.
Trolls are huge, muscular creatures with stone-like bodies. The ones seen in the animated series so far all resemble the troll depicted in the page image: large boulders, but with large stumpy arms and legs, with white blank eyes that seem to glow, and a large mouth with several sharp teeth. In the graphic novels however, Trolls come in a large variety of shapes and sizes.
By day, Trolls petrify into rocks under the influence of the sun. These Troll Rocks have the appearance of large boulders or stones that still vaguely resemble their true forms, with long nose-like protrusions. According to the troll information book seen in "Hildafolk", the petrification process is not a pleasant or comforatble experience, and on smaller and weaker trolls the effect can be permanent. As such, most trolls will try to avoid sunlight by hiding in caves or thick forests during the daytime. They rarely journey too far from their lairs to avoid getting caught out by the approaching sun.
However, when night comes, or if a Troll Rock is taken out of the sunlight through other means (like putting it in a darkened room), they will turn into their real appearance.
A lesser known fact is that when Trolls are close to their common ancestor Amma, they can sprout flowers and plants all over their bodies.
Trolls are very strong, even their children, and thus they can cause a lot of damage when angered.
They have their own language that, to humans, sounds like roars, growls and gargles, but is actually as sophisticated as the human tongue.
Trolls are meat-eaters by nature, but few of them actually eat humans. The unfortunate human-eating behavior of a few Trolls has given these creatures a bad name. However the majority pose no threat to humans and are content to live their lives undisturbed. Only if threatened will they attack. According to "Hilda and the Hidden People", Trolls are as wary of humans as humans are of them.
Trolls have a rich culture, and have their own celebrations. Most trolls like to hoard treasures. "Hilda and the Mountain King" shows that Trundle liked to collect gold and jewels, which can still be found in the ruins of his castle. But because these kind of valuables are hard to come by in this day and age, most trolls have settled for more modest objects to hoard. While being led around the Stone Forest by Baba's mom, Hilda encountered Trolls that hoarded car parts, barrels, bones, and even soft furnishings. Hoards are so important to Trolls, that they believe anything not kept in a hoard means its unwanted. This includes crops and pinned animals, cause as they see it, if the owner wanted it, it would be hidden away and guarded.
The greatest threat to Trolls is sunlight, since it petrifies them into motionless rocks and thus leaves them defenseless until nightfall. The Trolberg Safety Patrol have special guns called torches, that can fire rays with an effect similar to sunlight in order to fight trolls. Since they are vulnerable to attacks while in their petrified forms, some trolls take precautions to be unrecognizable as petrified trolls, like concealing their noses. Most trolls however hide from the sun during the day in dark places like caves or tunnels. Getting petrified at the wrong time can even be fatal to a troll, as proven when Trundle's body collapsed under it's own weight and fell apart after the Safety Patrol petrified him with their giant torch gun.
Trolls are afraid, or at least annoyed, by bells, a fact stated by Hilda in "Chapter 2: The Midnight Giant", and explained on an information page in "Hildafolk". Trolberg has multiple belltowers build into it's wall specifically to keep trolls away from the city. The reason why Troll don't like bells is because they experience the ringing of a bell much louder than humans, to the point that it hurts them, thus causing the trolls a great amount of psychological distress. Hilda discovered this herself when she was turned in to a troll in the story "Hilda and the Mountain King". In the movie adaptation, she even fears that getting too close to the ringing bells in Trolberg's belltowers might kill her. In the same story, Trundle was kept imprisoned in a cave with bells, and when he attacked the city, he first made sure to destroy the belltowers by throwing rocks at them from a safe distance.
As seen in "Hilda and the Stone Forest", Trolls are afraid of Rock-Chewing Slugs.
Trolls, or at least some of them, are capable of magic.
In both the graphic novels and the animated series + movie, Trylla is seen using magic to conjure a fire-like substance that she can shape into anything she wants. Among other things, she used this ability to create a campfire in her home, create a small woff-shaped ember to guide Johanna and Hilda out of the Stone Forest, and to show Hilda the story of the Mountain King. It is unknown if all Trolls can do this, or only a select few.
Another magical ability of trolls is to switch their children with human children; a process known as a Changeling. The human child will become a troll, complete with all the powers and weaknesses trolls have, while the troll child becomes human. The only known way to reverse the spell is to return both human and troll child to their real mothers. This happened to Hilda and Baba in "Hilda and the Mountain King", and in the cliffhanger at the end of Season 2 of the animated series.
According to Kaisa in the movie, Troll magic is not compatible with Witch magic, and the two cannot be used to counter each other. Frida discovered this the hard way when she tried a bodyswap spell to undo the changeling spell put on Hilda and Baba, only for it to backfire.
- Troll saliva can be used as glue. Hilda does this in "Hilda and the Hidden People" to scale a narrow path to the Caves of Kismet.