Hilding Gustaf Sigvard Ekström (9 October 1907[1] – 16 July 1995[2]) was a Swedish chemist, Waffen-SS volunteer, and co-founder of the Sweden Democrats party.

Ekström graduated as an engineer and moved to New Jersey in the United States in 1929, where he worked at an oil refinery and later as a sailor.

In 1932 he returned to Sweden and joined the Swedish National Socialist Party (SNSP) under the leadership of Birger Furugård, and a year later joined the Swedish Socialist Assembly (SSS) led by Sven Olov Lindholm.

He achieved the rank of SS-Rottenführer and served from 1941 to 1943 at the SS-Hauptamt in Berlin, where he translated, among other things, Swedish newspaper articles to German for the needs of Nazi Germany.

He was monitored by SÄPO since 1940 as he was classified as one of the most dangerous Nazis in Sweden and a potential traitor in the event of a German occupation.