Haakon Steen Lie (22 September 1905 – 25 May 2009) was a Norwegian politician who served as party secretary for the Norwegian Labour Party from 1945 to 1969. Coming from humble origins, he became involved in the labour movement at an early age, and quickly rose in the party system. After actively working for the resistance movement and the exiled government during World War II, he was elected to the second-highest position in the party after the war, and his years in office were the most successful in the party's history.