Eiso (英祖, c. 1229–August 31, 1299) was a semi-legendary ruler of Okinawa Island. He was the founding monarch of the Eiso dynasty.
The name Eiso superficially looks like a temple name but the scholarly consensus is that it represents Iso (伊祖), a settlement in modern-day Urasoe, Okinawa. Wezo no ikusamoi (good commander of Iso), who appears in the archaic poem collection Omoro Sōshi, is usually identified as Eiso.