Public Security Section 9 is a fictional gendarmerie-style information security and intelligence department from Masamune Shirow's Ghost in the Shell manga and anime series. In the franchise, its jurisdiction exists under the Ministry of Home Affairs. In some translations, the name is given as Public Safety Section 9. In the original film, it is known as the Shell Squad or Security Police Section 9. In the original publication of the manga, it was known as Mobile Armored Riot Police Section 9. Regardless of translation, when spoken of by the characters, it is simply referred to as Section 9.

GSG 9 der Bundespolizei, formerly Grenzschutzgruppe 9, is an elite special forces unit of the German Federal Police (Bundespolizei) to combat terrorism and violent and organized crime. In addition to its headquarters location in Sankt Augustin-Hangelar near Bonn, it has a second location in Berlin. Since 1 August 2017, it has been subordinate to the Federal Police Directorate 11. The state police (Landespolizei) maintain their own regional tactical units known as the Spezialeinsatzkommando (SEK). The GSG 9 unit is made up of approximately 400 highly trained police officers and the identities of GSG 9 members are classified. The specialised unit operates not only within Germany on a federal level, but also safeguards German interests located worldwide, such as embassy property and personnel. Alongside the KSK military special forces of the German Armed Forces (Bundeswehr), the GSG 9 can also be authorized to rescue citizens abroad in hostage situations.