Willem Fredrik Jacob Mörzer Bruyns, (born 1943 in Gosforth, Northumberland, United Kingdom), is a Dutch historian of navigational science, specializing in the history of navigational instruments; he has also published on the history of the Dutch in the Arctic in the nineteenth century.

The son of Willem Fredrik Jacob Mörzer Bruyns, Sr. (1913–1996), a Dutch merchant mariner, and a naval officer (reserve),[1] the young Willem Mörzer Bruyns initially trained as navigation officer at the [Amsterdam Nautical College] (Hogere Zeevaartschool van het Zeemanshuis), Mörzer Bruyns sailed as a junior officer with the Amsterdam-based Netherland Line.

In 1995 he was Huntington Fellow at The Mariners' Museum in Newport News, Virginia, and from 2005 to 2007 Sackler Research Fellow in the History of Astronomy and Navigational Sciences at the National Maritime Museum, Greenwich in London.

[2] In 2003, the University of Leiden awarded him a Ph.D. for his thesis on the introduction, diffusion and manufacturing of the octant in the eighteenth century Dutch Republic, completed under the guidance of Professor Jaap R. Bruijn and Professor C.A.

On his retirement Mörzer Bruyns was presented with a festschrift, Koersvast: Vijf eeuwen navigatie op zee (Zaltbommel: Uitgeverij Aprilis, 2005).