Jan Zamoyski (also known as Jan Zamojski, Ioannes de Zamość) (1542–1605), is a Polish-Lithuanian nobleman, magnate, 1st duke/ordynat of Zamość.

Royal Secretary since 1566, Lesser Kanclerz (Chancellor)) of the Crown since 1576, Lord Grand-Chancellor of the Crown since 1578, and Grand Hetman of the Crown since 1581.

General Starost of Kraków from 1580 to 1585, Starost of Bełz, Międzyrzecze, Krzeszów, Knyszyn and Derpsk.

Important advisor to Kings Sigismund II Augustus and Stephen Báthory, he is one of the major political opponents of Bathory's successor, Sigismund III Vasa.