Rhosus (Ancient Greek: Ῥωσός) is the name of several ancient sites and/or present Roman Catholic titular sees in what is now Turkey.

A titular bishopric in the former Roman province of Cilicia Secunda, suffragan to Anazarba. Rhosus or Rhossus was a seaport situated on the Gulf of Issus, later Alexandretta, southwest of Alexandria (modern Iskenderun or Alexandretta). It is mentioned by Strabo,Ptolemy,Pliny the Elder who places it in Syria and Stephanus Byzantius; later by Hierocles and George of Cyprus, who locate it in Cilicia Secunda.

Towards 200 AD, Serapion of Antioch composed a treatise on the Gospel of Peter for the faithful of Rhosus who had become heterodox on account of that book.Theodoret, who places it in Cilicia, relates the history of the hermit Theodosius of Antioch, founder of a monastery in the mountain near Rhosus, who was forced by the inroads of barbarians to retire to Antioch, where he died and was succeeded by his disciple Romanus, a native of Rhosus; these two religious are honoured by the Greek Church on 5 and 9 February.