Gérard Daniel Westendorp (8 March 1813, The Hague – 31 January 1869, Dendermonde) was a Dutch born, Belgian military physician and botanist.
Around 1834, he became a naturalized citizen of Belgium, subsequently serving as an assistant army and navy physician, later spending his career as a "regular doctor" in the Belgian army.
He also made significant contributions towards the "Prodromus Florae Batavae" project (1850-1866).
In the field of zoology, he published a treatise on Bryozoa and sponges of Belgium.
[3] Westendorp's botanical specimens are preserved in the Jardin Botanique National de Belgique.