Magnusson is a big, balding man with a grey beard and large eyebrows.
Magnusson is quite eccentric and a bit childish. He idolizes Edmund Ahlberg, the schools founder, and is very easy going towards the students. When the statue of Edmund Ahlberg that he was going to unveil during Parent's Night got smashed by a troll however, he considered this an epic disaster.
Role in the series
In "Chapter 5: The Troll Rock", he is overseeing the parents night at the Ahlberg School. He only really has eyes for the statue of Edmund Ahlberg however, and is counting down to the moment he gets to unveil it, which ultimately never happens. He thus misses most of the commotion surrounding the baby troll that got loose in the school.
In "Chapter 9: The Ghost", he is seen introducing the candidates for the upcomming presidential election. When he invites Frida to come up to the stage and give her speech, it turns out she's not there and he wonders if anyone has seen her.
In "Chapter 1: The Troll Circle", he is seen greeting Erik Ahlberg when the latter comes to pick up Hilda at the school. He is thrilled to have a descendant of Edmund Ahlberg visiting his school, and warns Eric that Hilda can be quite unpredictable.
In "Hilda and the Great Parade", Principal Magnusson takes over Ms. Hallgrim's role as the teacher who sees the Female troll when she comes to get her child back, and almost sounds the alarm but is convinced by Hilda not to do so. Another difference is that, rather than a statue, the troll wrecks the Ahlberg School's float for the Bird Parade (which depicted Edmund Ahlberg killing a troll). Principal Magnusson is thus forced to cosplay as Edmund Ahlberg on the float so the school can still participate. The events of "Chapter 9" are not included in any of the books.