Eilif Dahl (7 December 1916 – 17 March 1993) was a Norwegian botanist and politician for the Labour Party.
His interest in lichens started with an early friendship he developed with Professor Bernt Lynge.
According to Hildur Krog, his most important lichenological contribution was his 1950 work Studies in the Macrolichen Flora of SW Greenland, which was a revised version of his thesis.
During the German occupation of Norway he took part in resistance work, and was a member of the clandestine intelligence organization XU.
After fleeing to neutral Sweden and later to the United Kingdom, he served with the Norwegian High Command in London.