The most famous fascist militia in Italy was the Blackshirts, officially known as Milizia Volontaria per la Sicurezza Nazionale (MVSN). The main function of the Blackshirts were the defence of the fascist regime but it was also used for various police duties. It also raised Blackshirt battalions (that were assigned for regular army divisions), Blackshirt Divisions (made up of only Blackshirt troops), handled post-military training and supplied personnel to various other military tasks, such as air-defence.
Apart from the Blackshirts several other militias existed:

The Anti-Aircraft Militia (Milizia Controaerei) was formed 1927 and was responsible for the Anti-Aircraft defence of Italy (as opposed to the Anti-Aircraft units operated by the military) and also provided personnel for searchlight units and the Observation Service.

The Coast Defence Militia was formed 1932 and was responsible for manning the coastal batteries.

The Colonial Militia was formed in the Italian colonies, Libya and Italian East Africa (Eritrea, Ethiopia and Somalia).

The Fascist Albanian Militia was formed September 1939 in the Italian occupied Albania.

The Forestry Militia (Milizia Forestale) was formed 1926 and was used both for protection and exploitation of the nature and wildlife. Some front-line units were also formed from the Forestry Militia. It was controlled by the Ministry of Agriculture and Forests.

The Frontier Militia (Milizia di Frontiera) was formed 1927 and was made up of units from the MVSN used for guarding the frontiers against smuggling and illegal border crossings.

The Highway Militia (Milizia Nazionale della Strada) was formed 1928 and was used for (road) police duties. It was controlled by the Ministry of Public Works.

The Port Militia (Milizia Portuaria) was formed 1924 and guarded the main ports in both Italy and its colonies. It was controlled by the Ministry of Communications.

The Post and Telegraph Militia (Milizia Postelegrafonica) was formed 1925 and was used in peacetime to prevent fraud in postal, telephone and telegraph services. During wartime it was used for censorship and Field Postal Service. It was controlled by the Ministry of Communications.

The Railway Militia was formed 1923 and was used in peacetime as railway police and during wartime as soldiers protecting the railways. It was controlled by the Ministry of Communications.

The University Militia (Milizia Universitaria) was formed 1931 and was made up of university students undergoing reserve officers training. Front-line units were also formed from the University Militia.