Richard Otto Zöpffel (June 14, 1843 - January 7, 1891) was a German church historian and theologian born in Arensburg, Governorate of Livonia, Russian Empire (today Kuressaare, Estonia).
He studied theology in Dorpat, and history at the University of Göttingen under Georg Waitz (1813-1886). In 1871 he published Die Papstwahlen vom 11. bis 14. Jahrhundert (Papal Electrons from the 11th to 14th Centuries), and based on this work received his doctorate in Göttingen. Shortly afterwards he was appointed associate professor of church history at the University of Strasbourg, becoming a full professor in 1877. In 1887-88 he was rector of the university.
With Heinrich Julius Holtzmann (1832–1910) he created the influential Theologie und Kirchenwesen (Glossary of Theology, first edition-1882), and contributed many articles to the Realencyklopädie of Herzog, Plitt, and Hauck.