Lythe, Robert (d. c. 1574), cartographer, was first recorded in 1556 when he was employed by the auditor of Calais, John Challoner (qv), to map the surrounding English Pale. Chaloner, a client of Sir William Cecil, became secretary of state to the Irish council in 1560 and is likely to have been responsible for the employment of Lythe in 1567 to map the newly pacified province of Ulster for Cecil, who regarded ‘lineal descriptions’ (CSPI, 1596–7, 368) as important administrative tools. The lord deputy, Sir Henry Sidney (qv), planned to extend the project to the whole country.
Lythe began work in September 1567 in Carrickfergus, where he drew two maps of the town, one of them as it stood and the other with Sidney's proposed fortifications. Bad weather and the lack of trustworthy guides prevented him from going further, and he returned to England. He took up his next Irish commission in November 1568 with instructions to map the lordships of Cooley, Omeath, Newry, and Mourne in Co. Louth and Co. Down, where the government was contemplating an exchange of territory with the local magnate Sir Nicholas Bagenal (qv). Lythe submitted his map of the country southwards from Strangford Lough to Dundalk in 1569 and then, due to the deteriorating political situation, was commissioned to survey the southern provinces. He returned to Dublin about October 1570, reportedly lame and almost blind, having surveyed all the country south of a line from Killary harbour to Strangford Lough, with the two exceptions of the lordships of Ormond and Ely O'Carroll.
Sidney lodged him in his own house and he had sufficiently recovered by the following spring to produce two new regional maps, one of the lordship of the earl of Thomond and the other, specially requested by the queen, showing the troublesome territories of the white knight and the knight of the valley. Two general maps were also in progress: the first, a map of southern Ireland which shows exactly the area that Lythe said he had surveyed, is well preserved; the second, of which the original is now lost, covered the whole of Ireland, and Lythe reported to Cecil that it measured 8.5 ft by 5.5 ft (2.6 m by 1.7 m) (about three-and-a-half miles to the inch). Illness forced him to leave Ireland in November 1571, and although the earl of Essex (qv) (1541–76) made a request for him to be sent back in November 1573 he does not appear to have returned. In 1574 he made a map of the Isle of Sheppey and helped to plan new fortifications at Swaleness in Kent. There is no later record of him and it is likely that he died soon afterwards.
Although Lythe's maps were never published under his own name, his pioneering work was extremely influential. It was extensively copied by other artists in the 1580s, began to appear in print in the 1590s, and served as an important source for the well known series of maps published in John Speed's (qv) collection, Theatre of the empire of Great Britaine (1612).