Bagn is the administrative centre of Sør-Aurdal municipality, Norway. Its population (SSB 2005) is 687.

James Eustace Bagnall ALS (7 November 1830 – 3 September 1918) was an English naturalist with a particular interest in botany, especially bryology. He was the author of the first Flora of Warwickshire (VC38) in 1891. A noted bryologist, he wrote the Handbook of Mosses in the Young Collector Series, various editions of which were published between 1886 and 1910.