The Viannos massacres (Greek: Σφαγές της Βιάννου / Ολοκαύτωμα της Βιάννου) were a mass extermination campaign launched by German forces against the civilian residents of around 20 villages located in the areas of east Viannos and west Ierapetra provinces on the Greek island of Crete during World War II.

Viannos is a mountainous area in the southeastern part of Heraklion regional unit, stretching between the feet of Mount Dikti in the north and the Libyan Sea in the south coast of Crete.

[7] In early 1943, the increasing activity of guerrillas combined with the rumors that the Allies had plans to invade Crete, led the Italians to start the construction of coastal fortifications and install garrisons in the region.

In May 1943, they also established an outpost with three men in Kato Simi that were in charge of collecting potatoes for the provision of occupation troops and keeping the surroundings under surveillance.

[9][10] As historian Antony Beevor notes, Bandouvas acted without consulting the British; he anticipated that the Allies would soon land, and hoped that he would emerge as a national hero when they did so.

[13] The bodies of the two German soldiers stationed in Kato Simi were discovered and news of the incident reached their superiors, who ordered an infantry company to move to the village and investigate their fate.

[citation needed] On the day following the elimination of the company in Kato Simi, a large German force numbering more than 2,000 men started to gather in Viannos.

Exasperated by the loss of his men and wanting to set an example for fleeing Italians who were considering joining with the partisans, the commander of Heraklion, Friedrich-Wilhelm Müller, ordered soldiers from the 65th Infantry Regiment of the 22nd Air Landing Division (which formed part of the German garrison) to destroy Viannos and summarily execute all males over the age of 16 as well as everyone who was arrested in the countryside, irrespective of gender or age.

On the following day, indiscriminate mass executions, impromptu shootings and arrests, as well as looting, arsons, vandalism, demolition and destruction of harvests, were carried out by the Germans.

[12] The exact number of Greek victims remains unknown but most sources agree that the number exceeds 500,[10] consisting of inhabitants of the villages of Kefalovryssi, Kato Simi, Amiras, Pefkos, Vachos, Agios Vassilios, Ano Viannos, Sykologos, Krevatas, Kalami and Loutraki (in Greek: Κεφαλοβρύσι, Κάτω Σύμη, Αμιράς, Πεύκος, Βαχός, Άγιος Βασίλειος, Άνω Βιάννος, Συκολόγος, Κρεβατάς, Καλάμι, και Λουτράκι) in east Viannos as well as those of Myrtos, Gdochia, Riza, Mournies, Mythoi, Malles, Christos and Parsas (present day Metaxochori) (Μύρτος, Γδόχια, Ρίζα, Μουρνιές, Μύθοι, Μάλλες, Χριστός and Παρσάς - Μεταξοχώρι) in east Ierapetra.