Gerhardus (Gerard) Diephuis (6 February 1817, Farmsum – 4 November 1892, Groningen) was a Dutch jurist. After studies in Groningen, he was a judge with the arrondissement court in Winschoten and later with a higher court in Groningen. In 1840 he married Alagonda Geertruida Hemmes, with whom he had ten children. In 1859 he became a full professor at the university of Groningen. During the period 1864–1865 he was the rector magnificus of this institution.