Hartvik or Hartvic (also Arduin, German: Hartwig; died after 1103) was a prelate (most probably the bishop of Győr) in the Kingdom of Hungary under King Coloman the Book-lover.
[2] Based on the fact that Arduin of Ivrea, an 11th-century claimant to the title King of Italy, was referred to as Hartvigus in contemporary German sources, historian Gyula Pauler considered that Hartvik is identical with that episcopus Ioviensis Arduin, who – alongside a certain comes Thomas – was sent by King Coloman of Hungary to the court of Roger I of Sicily in 1097 to propose marriage to Roger's daughter.
A now lost royal charter of Coloman issued in 1103, recorded by 18th-century historian Miklós Schmitth, mentioned Bishop Arduin of Győr among the witnesses.
Beside the veneration of Stephen I, Hartvik's legend served justified the political purposes of Coloman in order to defend his royal prerogative to appoint the prelates of his realm, as a response to the Gregorian Reform and the Investiture Controversy.
[2] With some modifications in the text, Pope Innocent III sanctioned the Legenda Hartviciana as the official hagiography of Stephen I of Hungary in 1201.