Thomas Harriot (c. 1560 – 2 July 1621) was an English astronomer, mathematician, ethnographer, and translator. Some sources give his surname as Harriott or Hariot. He is sometimes credited with the introduction of the potato to Great Britain and Ireland. After graduating from the Oxford University, Harriot traveled to the Americas on expeditions funded by Raleigh, and on his return he worked for the 9th Earl of Northumberland. At the Earl's house, he became a prolific mathematician and astronomer to whom the theory of refraction is attributed.