Petrus Johannes Blok (10 January 1855, in Den Helder – 24 October 1929, in Leiden) was a Dutch historian.
Blok believed that it was the task of a historian to stress a country's national past and contribute to a sense of unity.
His books are biographical in nature and are about Dutch heroes: Oranje (1919–1920), Frederik Hendrik (1924), and De Ruyter (1928).
It is a book about people, but not a real social history; Blok's magnum opus has unfavorably been compared to Pirenne's famous Histoire de Belgique (1909–1932).
(The English translation, by Ruth Putnam and Oscar A. Bierstadt, of Blok's book, History of the people of the Netherlands, is abridged and has five volumes.)