According to older historiography, Iljko was a duke (Croatian: [[knez (title)|knez]]) in Croatia from 876 until 878, and a member of the Domagojević dynasty, probably the son of Domagoj.[1]
However, it has later generally been accepted that his name was a consequence of a wrong translation of the Chronicle of Dandolo, a Latin text written by Andrea Dandolo in the 14th century.[2] The name of the unknown prince was probably the result of Dandolo's fantasy. During the specified timespan a son of Domagoj ruled Croatia, but his name was not preserved.