Mille-Marie Treschow born in Larvik is a Norwegian estate and forest owner and business woman. Mille-Marie Treschow is the daughter of estate owner Gerhard Aage Treschow and Nanna, née Meidell.
Of her second marriage (1984–2000), with Andreas Stang, Treschow has two children.
In 2004 she married Stein Erik Hagen. In 2012 they announced their separation. Treschow belongs to the Danish and Norwegian noble family of Treschow. Treschow owns and resides at the Castle of Fritzøehus.
Mille-Marie Treschow has been a pupil at Croft House School in Dorset, England. She has also Norwegian examen artium. She received a Master of Business Administration in Switzerland, and she has additionally economic studies from the United States of America and home economic studies from France.
Her previous marriage to Andreas Stang produced two children, Michael Andreas Stang Treschow, born in 1986, and Victoria Stang Treschow, born in 1989. .
She was a keen rider from early on, and played handball at a county level. She is also very interested in sailing, and oceanic activities. Together with her husbond she reportedly owns one of the biggest sailboats in Europe.
She currently lives at Frizøehus, which is one of the most lavish privately owned manor houses in Norway. With its 96 rooms, it is the second largest occupied home after the Royal Palace in Oslo. The ground surrounding the manor, is comprised of English gardens, sculpture gardens with Vigeland-sculptures and forests that cover an area of about 70 acres.
Usually the eldest son inherited the family businesses and the properties. But a series of unfortunate accidental deaths and tragedies during the 20th century, has led to Treschow being in charge of the family and the company.
Her father took over the business because his elder brother was killed in an avalanche in 1947. Her brother died together with the young Løvenskiold, of the neighboring noble family of Løvenskiold in Skien, in what appears to have been a shooting accident.
The only thing found was the gun and the two young boys, which led to discreet speculations of collective suicide or murder. Her aunt was paralyzed in a diving accident, and died in 1952, only 39 years old.
Based in Larvik, Treschow manages an extensive consortium Treschow Fritzøe consisting of properties and forest as well as industry, trade, and other enterprises. Succeeding her father in 1986, she is the 6th generation owning and running the family industry. Fritzøe consisted of forest and soil properties along Siljan and Numedalsvassdraget. Charcoal and timber from forests and water power from the river between Farris and Larviksfjord formed the basis for the development of industry along the Farris river, which in turn laid the foundation for the development of Larvik.