Henry I Sinclair, Earl of Orkney and feudal baron of Roslin (c. 1345 – c. 1400), was a Scottish nobleman. He is best known today from a modern legend that claims he took part in explorations of Greenland and North America almost 100 years before Christopher Columbus. In 1784, he was identified by Johann Reinhold Forster as possibly being the Prince Zichmni described in letters allegedly written around 1400 by the Zeno brothers of Venice, in which they describe a voyage throughout the North Atlantic under the command of Zichmni.