Serafino Mazzolini (9 June 1890 – 23 February 1945) was an Italian lawyer, fascist politician, and journalist.
In 1918, Mazzolini returned to Ancona and was deputy editor of L'Ordine newspaper, interrupting his assignment in order to join Gabriele D'Annunzio as the latter attempted to seize Fiume for an "unredeemed" Italy (1919).
In quick succession, he renounced all PNF political missions, and returned to journalism for a while, before beginning a career in diplomacy.
After Mussolini's ousting and the Armistice of Cassibile (8 September 1943) between Italy and the Allies, Mazzolini joined the Nazi German-backed and Mussolini-led Italian Social Republic, serving as its deputy-secretary for Foreign Affairs.
He died at San Felice del Benaco as the result of a sepsis produced by an insulin injection.