James Rosier (1573–1609) was an English explorer, notable for his account of a 1605 expedition to America, in which he describes native peoples and fauna of northern New England.

After his father's death in 1581, he was brought up in Ipswich by Robert Wolfrestone, a relative of his mother's, and then in Sir Philip Parker's household.

[3] About that time he met Thomas Arundell, who hoped to establish a colony in America for his fellow Catholics.

Arundell joined with Plymouth merchants and perhaps his brother-in-law, Henry Wriothesley, 3rd Earl of Southampton, to set forth an expedition under Captain George Weymouth to explore the Maine coast.

[4] According to Quinn, there were three versions of Rosier's account of the voyage: a now-lost journal; a manuscript version obtained first by Hakluyt and then by Purchas, who abridged it in Purchas his Pilgrimes in 1624; and yet another manuscript, perhaps edited by Hakluyt, which was published as A True Relation of the most prosperous voyage made this present year by Captaine George Waymouth in the Discovery of the Land of Virginia: where he discovered 60 miles of a most excellent River; together with a most fertile land, (London, 1605).