Ms. Hallgrim is a short, elderly woman with dark skin and white hair. She also wears glasses.
In her younger days, she had brown hair.
Ms. Hallgrim is quite a strict teacher that values discipline and students following protocols. It's because of this she and Hilda got off on the wrong foot. She is also not above being biased towards students that she believes are unfit for her class. For example, when during the Parent's Night in "Chapter 5: The Troll Rock" a baby troll caused trouble in the school, she immediately assumed Hilda to be the culprit.
However, after Hilda stood up to an adult Troll that came to get her lost baby back, Ms. Hallgrim warmed up to her and allowed her to stay in her class.
In the novel "Hilda and the Great Parade", Ms. Hallgrim is depicted as even stricter than in the animated series, and gets into more arguments with Hilda.
So far, Ms. Hallgrim only had a major role in "Chapter 5". In this episode, she is in charge of the parent's night at the Ahlberg School. She tried to use this opportunity to talk in private with Johanna about Hilda, whom she believed should be put in a special class due to her behaviour in school. This was increased even further when strange things begin to happen during the parents night, like someone throwing a rock at a projector. Ms. Hallgrim believed Hilda to be responsible, while in fact the culprit was a young Troll that David had accidentally brought to school as part of his rock collection.
During the episode, Hilda, David and Frida desperately tried to keep Ms. Hallgrim from realizing the truth, since if word got out what David did he could get sent to jail. When the sun set, and the Troll began to wreck havoc in the school, Ms. Hallgrim again believed Hilda to be responsible. She finally managed to get to talk to Johanna in her office, but fortunately for Hilda, Johanna stood up for her. It was then that the mother of the baby troll attacked the school, and Hilda got a chance to show Ms. Hallgrim her talent for befriending dangerous creatures. She returned the baby troll to it's mother, and convinced Ms. Hallgrim to keep silent about what happened.
Ms. Hallgrim also had a brief appearance in "Chapter 9: The Ghost", in which she told Frida that she had accidently handed in last weeks homework. This further underminded Frida's at the time already low self-image, and made her nervous enough to consider dropping out of the Class President election.
In "Chapter 1: The Troll Circle", she can be seen among the students and staff of the school as Hilda is picked up by Erik Ahlberg to go on patrol with him. In "Chapter 6: The Old Bells of Trolberg", she can be seen reacting to Ahlberg activating all the bells in Trolberg.
In "Chapter 8: The Fifty Year Night", when Hilda traveled 50 years back in time, she briefly encountered a young Hallgrim and her mother.
The events from "Chapter 5: The Troll Rock" are adapted into the book "Hilda and the Great Parade". Like in the episode, Ms. Hallgrim and Hilda don't get along well. Early in the story, Ms. Hallgrim assigns Hilda, David and Frida to the same group for the Wonderful Trolberg project, where the class has to make an exhibition for parents night. But after receiving complaints from both David's and Frida's parents regarding Hilda's behavior, she forces Hilda to complete the project alone.
Her role during the adventure with the Baby troll is slightly downplayed; instead of her, it is Principal Magnusson that almost sounds the alarm when the Female troll shows up at the school to get her child back. The last that is seen of Ms. Hallgrim in the book is that she faints when she hears Alfur (who is trapped inside a lamp and whom she can't see) talk.
- "Chapter 5: The Troll Rock"
- "Chapter 9: The Ghost"
- "Chapter 1: The Troll Circle" (non-speaking cameo)
- "Chapter 6: The Old Bells of Trolberg" (cameo)
- "Chapter 8: The Fifty Year Night" (cameo in the past)
- The novel "Hilda and the Great Parade" claims that she teaches Class Four B. In the animated series, her class is not given a name.
- Her first name was only revealed in the episode "Chapter 8: The Fifty Year Night", where Hilda encounters Enid as a child.