William Marsden FRS FSA (16 November 1754 – 6 October 1836) was an Irish orientalist, numismatist, and linguist who served as Second, then First Secretary to the Admiralty during years of conflict with France.

Upon obtaining a civil service appointment with the East India Company at sixteen years of age, he was sent to Benkulen, Sumatra, in 1771.

He had been recommended by James Rennell, Edward Whitaker Gray, John Topham, Alexander Dalrymple, and Charles Blagden.

As first secretary he suggested a system later named Marsden squares for arranging and grouping information over the oceans.

[8] His other works are Catalogue of Dictionaries, Vocabularies, Grammars and Alphabets (1796), Numismata orientalia (London, 1823–1825), and several papers on Eastern topics in the Philosophical Transactions and the Archaeologia.