Gustloff (a son of merchant Herrmann Gustloff - info from Günter Grass's Crabwalk), who worked for the Swiss government as a meteorologist, joined the NSDAP in 1929. He put much effort into the distribution of the antisemitic propaganda book The Protocols of the Elders of Zion, to the point that members of the Swiss Jewish community sued the book's distributor, the Swiss NSDAP/AO, for libel. Gustloff was shot and killed in 1936 by David Frankfurter, a Croatian Jewish student incensed by Gustloff's antisemitic activism. Frankfurter surrendered immediately to the Swiss police and was sentenced to 18 years imprisonment (and was subsequently pardoned in May 1945).
Gustloff's assassin spent the war in a Swiss prison. He was pardoned and exiled at the end of the Second World War.
Gustloff was given a state funeral in his birthplace of Schwerin in Mecklenburg, with Adolf Hitler, Joseph Goebbels, Hermann Göring, Heinrich Himmler, Martin Bormann and Joachim von Ribbentrop in attendance. Thousands of Hitler Youth members lined the route. His coffin, transported on a special train from Davos to Schwerin, made stops in Stuttgart, Würzburg, Erfurt, Halle, Magdeburg and Wittenberg. Gustloff's widow, mother and brother attended the funeral and received personal condolences from Hitler. Ernst Wilhelm Bohle was the first at Gustloff's funeral to recite a few lines in his honour.
Gustloff was proclaimed a Blutzeuge of the Nazi cause and his murder became part of the propaganda that served as pretext for the 1938 Kristallnacht pogrom. His wife Hedwig, who had been Hitler's secretary, received from Hitler personally a monthly "honorary pay" of 400 Reichsmark, the equivalent of some $13,000 today.
Gustloff's death was not immediately politicized as the assassination of the German diplomat Ernst vom Rath by Herschel Grynszpan in Paris was in 1938 to incite Kristallnacht. Hitler did not want to risk any domestic bouts of anti-Semitism costing Germany losing the recently awarded right to host the 1936 Summer Olympics, since his anti-Semitic policies had already led to calls to relocate the games.
The German cruise ship MV Wilhelm Gustloff was named for Gustloff by the Nazi regime. The ship was sunk by a Soviet submarine in January 1945 in the Baltic Sea while carrying mostly civilian refugees from the advancing Red Army. More than 9,000 lives were lost, the greatest death toll from the sinking of a single vessel in human history. The disaster remains relatively little known.
The Wilhelm Gustloff Foundation (or Wilhelm-Gustloff-Stiftung) was also named after Gustloff. The small arms factory Berlin Suhler Waffen und Fahrzeugwerke was renamed Wilhelm Gustloff Werke in Gustloff's honour in 1939.