Bård Lappegård Lahn (born 26 May 1983 in Stange, Norway) is a Norwegian environmentalist and in 2006 and 2007 chairman of Natur og Ungdom. Prior to his leadership he had been deputy chairman since 2003 and an active member og Natur og Ungdom since the mid-1990s. Lahn now works as an adviser on international climate policy in the Norwegian Society for the Conservation of Nature, and serves on the board of the Sophie Prize. In the early 1990s he had his own section in Newtons Hage on the national TV channel Norsk Rikskringkasting.