Cassius Apronianus was a senator of Roman who lived in the 2nd century. He married the daughter of Greek historian, orator, and philosopher Dio Chrysostom. Their son was Roman historian, consul and senator Cassius Dio.
Apronianus was originally from Bithynia (modern North-Western Turkey), and a member of the gens Cassius. He was governor of Lycia et Pamphylia around 179/180, then of Cilicia (modern Southern-Eastern Turkey) c. 180 - c. 183, where he was joined by his son Dio. Apronianus became suffect consul most likely around 185, after which he served as governor of Dalmatia (modern Dalmatia, Croatia).