Marius Borg Høiby (born 1997) is the eldest son of Mette-Marit, queen of Norway and the stepson of King Haakon VIII. He was born during a brief relationship she had with Moren Borg, who had served time in prison for assault and possession of cocaine. After Høiby’s birth, she worked to support herself while raising him as a single mother. In 2001 she married Crown Prince Haakon. Høiby was not given a royal title, and he has no official duties.
In August 2024 he was arrested on allegations that he had assaulted his girlfriend. Days later he apologized for the incident and noted that he had been under the influence of cocaine and alcohol and would seek treatment. In the ensuing months, Høiby faced rape allegations involving various women, and in June 2025 he was formally charged on multiple counts of rape and sexual assault. Days before his trial was to begin in February 2026, he was arrested and accused of several crimes, including assault. In June Høiby was convicted of two counts of rape and various other offenses. He was sentenced to four years in prison.