Gustav Mattias Anton Kasselstrand (born 27 June 1987) is a Swedish politician, serving as leader of Alternative for Sweden (AfS) since 2018. He was chairman of the Sweden Democratic Youth (SDU) from 2011 to 2015 and served as political secretary to the Sweden Democrats in the Riksdag from 2011 to 2012. Kasselstrand was expelled from the Sweden Democrats on 27 April 2015 but remained as chairman of the SDU until 12 September 2015, when Jessica Ohlson succeeded to the post and the Sweden Democrats subsequently cut their ties with the youth league.