Johannes Dou

Johannes Dou (1615–1682), also known as Jan Jansz. Dou or Jan Janszoon Douw, was a Dutch land surveyor and cartographer primarily active in the mid-17th century. Born in Leiden, he studied at the University of Leiden and was admitted as a land surveyor by the High Court of Holland in 1635.

Dou is noted for his work on detailed maps, especially for water management and regional topography, working for organizations such as the Hoogheemraadschap (regional water boards). His contributions were important for Dutch cartography, particularly in managing the complex waterways of the Netherlands.