Madoc ab Owain Gwynedd was, according to folklore, a Welsh prince who sailed to the Americas in 1170, over three hundred years before Christopher Columbus's voyage in 1492.

Owain ap Gruffudd was King of Gwynedd, North Wales, from 1137 until his death in 1170, succeeding his father Gruffudd ap Cynan. He was called Owain the Great and the first to be styled "Prince of Wales", and the "Prince of the Welsh". He is considered to be the most successful of all the North Welsh princes prior to his grandson, Llywelyn the Great. He became known as Owain Gwynedd to distinguish him from the contemporary king of Powys Wenwynwyn, Owain ap Gruffydd ap Maredudd, who became known as Owain Cyfeiliog.