Hendrik Pieter Nicolaas Muller, GON, RNL, FRGS (2 April 1859 in Rotterdam - 11 August 1941 in The Hague, Netherlands) was a Dutch businessman, diplomat, world traveller, publicist, and philanthropist. He was a son of Hendrik Muller Sz., a Rotterdam-based Dutch businessman and politician, and Marie Cornelie van Rijckevorsel, member of another prominent Rotterdam based business family.
Muller started his career as a businessman, trading with East and West Africa. In his mid-twenties he travelled to Zanzibar, Mozambique, and South Africa for business purposes, but showed himself a keen ethnographer as well, collecting ethnographic artifacts and writing reports about the societies and people he encountered on his way. In 1890, Muller retired from business for personal reasons, and went to Germany to study ethnography and geography. He graduated with a Ph.D. dissertation four years later.