The Naumann Circle (German: Naumann-Kreis), also sometimes referred to as the Gauleiter Circle or the Naumann Affair, was an organization of former German adherents of the Nazi Party that was formed in the German Federal Republic (West Germany) several years after the end of the Second World War. It was founded and led by Werner Naumann, the last State Secretary of the Reich Ministry of Public Enlightenment and Propaganda. Between 1951 and early 1953, the organization attempted to infiltrate the Free Democratic Party (FDP) and two smaller parties to lay the groundwork for a possible return to power. British security forces disrupted the cabal by arresting Naumann and several of his associates in early 1953. Handed over to West German authorities, the accused were investigated but the charges ultimately were dismissed by the criminal court due to insufficient evidence.

Werner Naumann (1909–1982), studied law and political science and earned a doctorate in 1936. A member of the Nazi Party from 1928, he became a skilled propagandist and SS-Brigadeführer and, from 1938, worked directly with Joseph Goebbels, the Reichsminister for Propaganda. Naumann rose to become the State Secretary in the Ministry in April 1944 and was named in the Last will and testament of Adolf Hitler as Goebbels' successor as Reichsminister. Escaping from the Führerbunker in the closing days of the war, he went underground with an assumed name and worked as a farm worker, later completing an apprenticeship as a mason. He reemerged in early 1950 after an amnesty law had taken effect, and became the manager of an import-export company in Düsseldorf. The amnesty law was estimated to apply to some 800,000 individuals and it even applied to those Nazi officials and SS members who had assumed a false identity in 1945 in order to avoid prosecution.

Naumann soon began making contact with other former Nazi functionaries. It has been estimated that he developed a very wide network of contacts numbering perhaps as many as 1,000; his address book alone contained over 700 names. He set about organizing these contacts into an underground organization. His correspondence stressed the need for secrecy, and the organization made use of personal couriers, false addresses and code names. A series of regular monthly meetings began in February 1952. Naumann's contacts were not limited to Germany, but also included many Nazis who had fled abroad via the ratlines, such as Otto Skorzeny in Spain and Eberhard Fritsch, Johann von Leers and Hans-Ulrich Rudel in Argentina. He maintained frequent contact with these émigrés and the US CIA reported that, although his plans had not yet progressed to the point that he could direct their activities, he could expect their support whenever he decided to openly enter into political activities.

In addition to Naumann, the circle included many individuals who had held positions of responsibility in Nazi Germany, including seven of the forty-three Gauleiter, a number of his former colleagues in the Propaganda Ministry and many high-ranking Schutzstaffel (SS) officers, some of whom had been convicted of war crimes. The following is a partial list of the most prominent known members and associates:

The primary aim of the organization was to work in the background to place a few hundred trusted men into key positions in military veterans associations, in organizations of farmers and small businessmen and in local administrations, and to turn them into a strong, unified force that eventually could supplant the established democratic parties. In addition, they sought to place adherents into leadership roles in the parties themselves, to enable them to influence and seize control of the parties from within. Naumann set about developing a plan to infiltrate existing political parties, with the main target being the Free Democratic Party (FDP), a secular, free-market oriented, centrist party. Two smaller more conservative parties, the German Party (DP) and the All-German Bloc were also to be penetrated. Naumann targeted the FDP and the DP in particular because, as mainstream parties and participants in the first coalition cabinet of Chancellor Konrad Adenauer, they could prove to be viable vehicles for advancing his viewpoints and policies. This contrasted with the overtly neo-Nazi Socialist Reich Party that, because of its extreme views, was found to be unconstitutional and was banned by the Federal Constitutional Court on 23 October 1952 on the basis of being a successor organization to the Nazi Party.

After the defeat of Nazi Germany in May 1945, former members of the Nazi Party underwent denazification procedures. This resulted in those judged to be "offenders" either being jailed, paying fines or being banned from participation in electoral politics. However, the vast majority of Party members were determined to be "followers" or "exonerated" and never faced criminal prosecution or civil penalties. These individuals joined various political parties, including the FDP. The FDP Bundestag members at the end of 1950 voted in favor of ending the denazification process altogether, thus attracting additional support from former Nazis. At their party conference in Munich in 1951 the FDP demanded the release of all "so-called war criminals" and welcomed the establishment of the Verband deutscher Soldaten [de] (German Soldiers' Association), an organization of former Wehrmacht and SS members, in order to advance the integration of former Nazi forces into the political system. In particular, the very nationalist FDP state association of North Rhine-Westphalia, under the leadership of Friedrich Middelhauve, enthusiastically welcomed ex-servicemen and former Nazi Party members in order to expand its voter base to the right. Ernst Achenbach, as a state Landtag member, together with Werner Best, coordinated a campaign to advocate for a general amnesty for war criminals. He and Middelhauve envisioned creating a unified organization of all the right wing parties along the lines of the Weimar Republic-era Harzburg Front, an effort they dubbed the Nationale Sammlung (National Collective).

In the summer of 1952, Middelhauve presented to the state party conference in Bielefeld the so-called "German Program", which had been formulated largely with input from Naumann, Best, Fritzsche and Six. The text included revanchist ideas such as refusing to renounce the right of expelled Germans to return to their home territories, and also voiced objections to the Allies judgments of former soldiers. Middelhauve presented the program at the FDP federal party conference at Bad Ems in November 1952 but it was not adopted at the federal level, in order to forestall a split in the party. Nevertheless, Middelhauve emerged from the party conference strengthened when he was elected as one of two deputy party leaders. In the municipal elections of November 1952, some fifty former Nazi officials in North Rhine Westphalia were elected to office as candidates of the FDP.

Many observers were alarmed by the FDP's rightward shift. The Frankfurter Rundschau characterized the events at the party conference as the "intra-party January 30th of the FDP", referring to Adolf Hitler's 1933 assumption of power; France's Le Monde stated that the FDP was on the way to transforming itself into a "nationalist and reactionary movement of the extreme right". The FDP, along with the DP, was viewed as part of an "extremist" bloc in an analysis by US intelligence officials.