|"King of Parthia"|
|Coin of Phriapatius.|
|Arsaces II of Parthia|
|Phraates I of Parthia|
Phriapatius (Persian: فریاپت) /ˌfraɪəˈpeɪʃəs/) or Priapatius /ˌpraɪəˈpeɪʃəs/, sometimes called Phriapites /ˌfraɪˈæpɨtiːz/, ruled the Parthian Empire from 191 BC to 176 BC. He was the grandson of Tiridates I of Parthia (246–211 BC), the brother of Arsaces I of Parthia (250–211 BC), the founder of the Parthian Empire.
He ruled in the period following the invasion of Parthia by the Seleucid king Antiochus III (223–187 BC).
He was the father of three Parthian kings, Phraates I (176–171 BC), who was his successor, Mithridates I (171–138 BC), and Artabanus I (138–124 BC).