Robertus Wilhelmus Maria van Soest, born in 1946,[1] is a Dutch marine biologist.

He works at the Naturalis Biodiversity Center and is also affiliated with the University of Amsterdam.

He co-authored with John N. A. Hooper Systema Porifera: A Guide to the Classification of Sponges,[2] a standard reference for sponge classification.

[7] He has contributed to the systematics, the phylogeny and the taxonomy of sponges,[8][9][10] to their chemistry[11] and biological properties (and the pharmacological use thereof)[12][13][14] His zoological abbreviation is van Soest.

He has authored (co-authored) over at least 170 peer reviewed scientific papers, over 60 of which concern the biochemistry of sponges.