Sofus Anton Birger Arctander (22 January 1845 – 20 August 1924) was a politician with the Liberal Party who served as acting Prime Minister of Norway during 1905.

He was deputy judge and then acting district stipendiary magistrate before establishing himself as a lawyer in 1875.

[2] In 1877, Arctander was elected deputy Member of the Parliament of Norway for the County of Nordland.

He was an honorary member and co-founder of the Nordlendingenes Forening, an association of people who have emigrated from the counties in Northern Norway.

Arctander died in the Lifjell Mountains of Telemark one day in August 1924, the exact date uncertain.