Hermanus Johannes de Graaf (2 December 1899 – 24 August 1984) was a Dutch historian specialising in the history of Java, Indonesia's most populous island. Trained as historian at Leiden University, he moved to Batavia (today's Jakarta) to take a government job, and later became a teacher for various schools in Indonesia. At the same time, he pursued his interest in the history of Indonesia and published books and articles on the topic. After a brief assignment at the University of Indonesia, he returned to the Netherlands. He taught at various institutions, including Leiden, until 1967 and continued to publish scholarly works, even after his retirement. He suffered a serious stroke in 1982 and died two years later.