Konrad Gustav Knudsen (19 August 1890 - 16 June 1959) was a Norwegian painter, journalist, and parliamentarian. Knudsen is perhaps best known for inviting Leon Trotsky to live at his house when the Norwegian government granted Trotsky political asylum in June 1935.
Knudsen returned to Drammen in 1920 and worked as a painter foreman until 1923, before he then got a job as an editor in the newspaper Fremtiden. From 1921, Knudsen held various positions within the Labour Party, and was elected to the Norwegian Parliament in October 1936, a position he would hold for the next 21 years, including in the 1940–1945 government in exile.
In June 1935, Knudsen invited Leon Trotsky and Natalia Sedova to live at his house, following their arrival in Norway after the French government had told Trotsky that he was no longer welcome in France. For over a year, Trotsky and his wife stayed at Knudsen's house at Norderhov outside the small city of Hønefoss, not far from the Norwegian capital Oslo, although Trotsky was hospitalized at the Oslo Community Hospital for a few weeks in the autumn of 1935. During his time living at Knudsen's house, Trotsky wrote one of his most famous books, The Revolution Betrayed, a book which was completed and sent to the publisher on 4 August 1936, just prior to the infamous Trial of the Sixteen, one of the Moscow show trials.