Iyannough (also Iyanough) was an American Indian sachem and leader of the Mattachiest (Mattakeese, a sub-group of the Wampanoag people) tribe of Cummaquid in the area of what is now Barnstable, Massachusetts.
When the son of Mayflower passenger John Billington wandered away from the new settlement at Plymouth in January 1621, Iyannough assisted in finding the boy.
A party of ten Pilgrims, including Edward Winslow (who is generally thought to be the author of the events) and two American Indians, the interpreter Tisquantum and "special friend" Tokamahamon, met Mattakeese tribesmen, and were invited to eat with them.
[1]They brought us to their sachem, or governour: whom they called Iyannough, a man not exceeding twenty-six years of age, but very personable, gentle, courteous, and fair conditioned, indeed not like a savage, save for his attire.
Yanno is mentioned in several land deeds on Cape Cod and Martha's Vineyard and appears to have been a prominent figure in the early settlement of the communities.