Christian Wirth (German: [vɪʁt] ^ⓘ; 24 November 1885 – 26 May 1944) was a German Schutzstaffel (SS) officer and leading Holocaust perpetrator who was one of the primary architects of the program to exterminate the Jewish people of Poland, known as Operation Reinhard. His nicknames included Christian the Cruel (German: Christian der Grausame), Stuka, and The Wild Christian due to the extremity of his behaviour among the SS and Trawniki guards and to the camp inmates and victims.

Wirth worked within the Action T4 program, in which people with disabilities were murdered by gassing or lethal injection, and then at implementing Operation Reinhard, by developing almost single-handedly, the extermination camps for the purpose of mass murder. Wirth later served as Inspector of all the Reinhard Camps. He was killed by the Yugoslav Partisans in Hrpelje-Kozina near Trieste after the conclusion of Operation Reinhard.

Christian Wirth was born on 24 November 1885 in Oberbalzheim, Württemberg, part of the German Empire. The son of a master cooper, after attending elementary and continuation school, Wirth learned the sawyer's craft. From 1905 to 1910, he was a member of the Württemberg Grenadier Regiment 123. By 1910 Wirth had worked as a policeman in Heilbronn, but he soon moved to Stuttgart, where he was a detective of the police.

During the First World War, at his own request, he served as a non-commissioned officer in the army on the Western front, distinguished himself in battle, was wounded, and was highly decorated. Wirth was awarded the Iron Cross First Class, Iron Cross Second Class, and the Order of the Crown (Württemberg). After the war Wirth returned to Stuttgart in June 1919 and was promoted back to police detective sergeant.

Wirth married Maria Bantel and fathered two children.

Wirth was one of the original members of the Nazi Party, joining for the first time in 1923, before it was outlawed briefly in Germany following the unsuccessful Hitler Beer Hall Putsch.

He again joined the Nazi Party as an Alter Kämpfer ("old fighter") on 1 January 1931 (#420,383). He joined the Sturmabteilung (SA) on 30 June 1933. From 7 December 1937 he was a volunteer of the Sicherheitsdienst (SD). On 10 August 1939, Wirth transferred from the SA to the Schutzstaffel (SS), attaining the rank of Obersturmführer (first lieutenant) by October (SS #354,464).

After the Nazi Party rose to national power in Germany, Wirth served in the Württemberg police force. He had previously been a police officer in 1910, before the onset of World War I. Wirth rose to become the captain of detectives (German: Kriminalkommissar) of the Kriminalpolizei (Kripo) in Stuttgart.^{[citation needed]}