The name Theon means Godly and is of Greek origin. Theon is a name that's been used primarily by parents who are considering baby names for boys.
Theon Greyjoy: Character name created by George R.R. Martin in his Song of Ice and Fire novels and Game of Thrones TV series. Theon of Smyrna, ( 70 - 135 CE) Greek philosopher who described how prime numbers, geometrical numbers such as squares, progressions, music and astronomy are interrelated.