Lorentzen or Bie-Lorentzen is a Norwegian family of Danish origin. Several members have been noted as shipping magnates and industrialists. Among its members are shipowner Erik Finn Lorentzen and industrialist Erling Lorentzen, who was married to Princess Ragnhild of Norway (known as Princess Ragnhild, Mrs. Lorentzen after her marriage), the eldest daughter of King Olav V of Norway. Several members of the family are in the line of succession to the British throne; at the time of her death, Princess Ragnhild was number 75 and her children Haakon, Ingeborg and Ragnhild Lorentzen follow directly after.
The family is descended from Hans Zachariassen (died ca. 1643), who was a merchant in Skælskør in Denmark. His son, customs official Hans Hanssøn Skielschøer (1636–1700), settled in Norway, and was the father of merchant in Holmestrand Lorentz Hanssøn (1668–1723). Two branches of the family are descended from his sons, the shipowners Ole Lorentzen (1699–1737) and Jørgen Lorentzen (1709–1752).
A branch of the family uses the double surname Bie-Lorentzen, with or without a hyphen.