| Louisa Holthuysen | |
| Birth Date: | 28 November 1824 |
| Birth Place: | Amsterdam |
| Death Date: | 30 January 1895 |
| Death Place: | Amsterdam |
| Nationality: | Kingdom of the Netherlands |
Sandrina Louisa Geertruida Holthuysen (1824 – 1895) was a Dutch art collector and founder of the Museum Willet-Holthuysen in Amsterdam.
Holthuysen was born in Amsterdam in the Netherlands as the only child of Pieter Gerard Holthuysen, a wealthy merchant who dealt in window glass and coal. Her father died in 1858 and in 1861 she married Abraham Willet and they proceeded to live a bohemian lifestyle, enjoying travel and art collecting. The art collection included items bought by her, of which the most expensive painting was a still-life by Blaise Alexandre Desgoffe that cost 5,000 guilders.[1]
Holthuysen died childless in Amsterdam in 1895, a few years after her husband. Her house and its contents, including the artworks, were left to the City of Amsterdam, conditional upon the building being used as a museum named after her and her husband.[1]