Giuseppe Bastianini (8 March 1899 – 17 December 1961) was an Italian politician and diplomat. Initially associated with the hard-line elements of the fascist movements he later became a member of the dissident tendency.
Bastianini was born in Perugia. At an early age he became a local fascist leader in Umbria where he garnered a reputation as a member of the hard-line intransigenti wing of the movement. Following the seizure of power Bastianini was appointed head of the Fasci Italiani all'Estero, a movement aimed at co-ordinating the activities of Italian fascists not currently living in Italy. He called on members to seek to diffuse proper Italian fascist ideas wherever they were living. This group gained a considerable following amongst Italian expatriates in the mid-1920s. Indeed, in 1925 he submitted a report to the Fascist Grand Council claiming to have groups in 40 countries worldwide.
Bastianini's activities brought him into conflict with Italian diplomats, who felt that his movement was overtly politicising their work. For his part Bastianini called for a complete reform of the diplomatic service, insisting that the only true Italians were also fascists and that therefore all diplomats should be convinced fascists. In the end Benito Mussolini pursued a middle ground by dismissing diplomats who had not declared for the National Fascist Party but also limiting the power of Bastianini's movement, which was taking on many of the functions of foreign affairs for itself, to ideological instruction, sport and charity work by restoring power to the Italian consuls. Bastianini resigned from his position as head of the Fasci Italiani all'Estero in late 1926.
Somewhat inevitably following his drive to replace established diplomats with fascists Bastianini entered the diplomatic service himself. During the 1930s he was ambassador to Poland and as a consequence he was one of those who helped to convince Mussolini to delay entry into the Second World War, knowing that Roman Catholic Poland was a country admired by many Italians. It was around this time that he also served as ambassador to the United Kingdom.