Ludwig Hermann Karl Hahn (23 January 1908 – 10 November 1986) was a German SS-Standartenführer, Nazi official and convicted war criminal.

Between 1972 and 1975, Hahn was the subject of two separate war crimes prosecutions in Hamburg, West Germany; both related to atrocities that occurred during his service with the SS in Warsaw.

The son of a prosperous farmer of the same name, Hahn was born on 23 January 1908, in the rural town of Eitzen, Uelzen district, Province of Hanover in what was then the German Empire.

Hahn went on to study financial law at the University of Göttingen where he became a member of the National Socialist German Students' League (NSDStB).

Hahn qualified as a lawyer after completing his clerkship in April 1935 and became a member of the National Socialist Association of Legal Professionals (NS-Rechtswahrerbund).

During the September Campaign, Hahn and his Einsatzkommando were heavily involved in the arrests and executions carried out as part of the Intelligenzaktion, a Nazi extermination operation targeting the Polish intelligentsia and other members of the nation's elite.

Between September–November 1939, Hahn took part in the mass-killings of Polish public officials, political activists, intellectuals and army officers in Katowice, Sanok, Rzeszow and Podlesie.

In this position Hahn served as SS leader Heinrich Himmler's personal emissary to the Nazi-allied government of the Slovak Republic under Jozef Tiso.

As Commander of the SiPo and the SD, Hahn would oversee a force of approximately 2,000 individuals; including a staff of 500-600 SS security personnel, as well as around 1,000 Polish police auxiliaries and several guard companies composed mostly of Ukrainian and Cossack collaborators.

In the summer of 1942, Hahn collaborated with SS-Brigadeführer Odilo Globocnik and other personnel associated with Operation Reinhard to carry out Grossaktion Warschau, the liquidation of the Warsaw Ghetto.

As a deputy officer to SS and Police Leader Jürgen Stroop, Hahn also had a leading role in the bloody suppression of the Warsaw Ghetto Uprising in April–May 1943.

During the August–October 1944 Warsaw Uprising by the Polish Home Army, Hahn served with the Waffen-SS, leading a battalion of 700 men in the southern districts of the city and later in the downtown area.

Following the capitulation of the uprising, Hahn supervised the deployment of the Verbrennungskommando (Cremation Details); groups of Polish prisoners forced to work clearing bodies and debris from the city's streets.

In February 1945, he was reassigned to Dresden, where he briefly served as Stabsführer (chief of staff) to SS-Gruppenführer Ludolf von Alvensleben, the Higher SS and Police Leader for the Elbe.

Hahn remained in Germany after 1945 and went into hiding in Bad Eilsen in the British occupation zone, working for several years as a laborer and farmhand.

Following an inquiry by the Central Office of the State Justice Administrations for the Investigation of National Socialist Crimes, Hahn was arrested by the West German federal police for his suspected involvement in the destruction of the Warsaw Ghetto.

Hahn was arrested a second time in December 1965 and held in pre-trial detention for two years, but was ultimately released again, owing to his poor health.

After a two-year review of the trial and the evidence, Hahn's appeal was rejected by the West German judiciary and he entered prison in March 1975.

During the appeals process, Hahn was also on trial in a different West German court; this case surrounded his alleged role in the deportation of an estimated 230,000 Jews from the Warsaw Ghetto to Treblinka.