Hostius was a Roman epic poet, who probably flourished in the 2nd century BC.
He was the author of a Bellum Histricum in at least seven books, of which only a few fragments remain. The poem is probably intended to celebrate the victory gained in 129 BC by Gaius Sempronius Tuditanus (consul and himself an annalist) over the IllyrianIapydes (Appian, Illyrica, 10; Livy, epit. 59). Hostius is supposed by some to be the doctus avus alluded to in Propertius (iii.20.8). According to Apuleius (Apologia x) and the scholia on Juvenal (vi.7), the real name of Propertius's Cynthia was Hostia (perhaps Roscia).
Fragments are located in F. Bührens, Fragmenta poetarum Romanorum (1884); A. Weichert, Poetarum Latinorum reliquiae (1830).