Karl

Karl is the brother of Kai and a resident of the kingdom of Snoob.

History
Karl was born in the kingdom of Snoob, where he grew up alongside his brother Kai. Apart from being Kai's sibling, little is known as to his occupation or role in the kingdom. It is however mentioned in Reunion Road that Kai used to have regular contact with his brother until Agnarr ordered to close the castle gates in an attempt to conceal Elsa's powers.

When Elsa and Anna expressed their intention to visit Snoob for the kingdom's harvest festival, Kai admitted to have been born and raised there, but dismissed the idea of meeting up with his brother as a "non-issue" as he may have forgotten about Kai after all those years. Elsa and Anna however insisted Kai to tag along with them and reunite with Karl, where the two brothers met each other again and participated in the kingdom's harvest festivities.

Comics

 * Frozen: Reunion Road