Defunct Former Hans Kennert Mattias Hedarv Karlsson (born 17 August 1977) is a Swedish politician, writer and public commentator who served as Leader of the Sweden Democrats in the Riksdag from September 2014 to November 2019.

Karlsson has also been described as one of the SD's chief philosophical idealogues having been responsible much of the party's current platform and shift in its beliefs.

During his studies at the university, Karlsson met Jimmie Åkesson, incumbent leader of the Sweden Democrats, Richard Jomshof and Björn Söder.

The group later became known as the "Scania Gang" or the "Fantastic Four" and worked to reform the Sweden Democrats and change its ideology in a more moderate direction.

"[6]Karlsson reported having gained his political convictions during his teenage years in Växjö as a result of conflicts with immigrant "kickers" gangs who were engaging in criminal activity in the area and what he described as his resentment towards the lack of Swedish pride and solidarity in society.

[7] In a 2011 interview with Expo, Karlsson stated that he first took notice of the Sweden Democrats in 1994 and attended a meeting of the local branch in Växjö but chose not join the party at first due to disagreeing with its more hardline stances under Anders Klarström which he considered racist.

His first important impact within the Sweden Democrats came in 2002, when he alongside Jimmie Åkesson and former leader Mikael Jansson reshaped the party's political programme.

[10][11] Karlsson has argued that conservatism played a role in Sweden's political stability and reputation for strong social structures until the late twentieth century.

In 2015, Karlsson received media attention after comparing Islam to Nazism, saying that the former is currently a bigger threat to national security.

[10] In February 2020, Karlsson announced his new think-tank Oikos, with members on the steering board such as Malcom Kyeyune, Asle Toje, the ethnographer Dan Korn, and the leader of New Direction, Naweed Khan.