Jacobus (Jacob) Merkelbach (Amsterdam, 29 April 1877–Amsterdam, 6 February 1942) was a Dutch photographer specializing in portraiture. The Rijksmuseum in Amsterdam holds a permanent collection of some 208 of his photographs which is available for both viewing and scientific research. Such research revealed that for some 28 of them he had used the now long-defunct Jos-Pe dye imbibition process, a technique common in early commercial photography.