Hostilianus , of its complete name Gaius Valens Hostilianus Messius Quintus (francized in Hostilien ), was the son of the emperor Dèce. Born with an unknown date, he died in June 251.

Hostilianus is one of two wire of the emperor Dèce (249 - 251), his older brother is Herennius Etruscus (249 - 251), his/her mother is Herennia Crepessenia Etruscilla.

When Trajan Dèce becomes emperor, it names its two sons Caesar into 250. In year 251 it names his Auguste oldest son, but this one dies in the combat against Goths, which devastates the provinces of the east of Balkans. A little later while wanting to recover the spoils piled up by the Goths, Dèce dies him too.

The governor of the province of Messiah, Trébonien Galle the fact of naming Auguste, and also takes the title and gives the title of Caesar to his son Volusien. In the current of June, he dies of a serious disease, undoubtedly the plague, and Volusien takes the title of Auguste in his place.

Successive names

• Is born Gaius Valens Hostilianus Messius Quintus
• 250, made César by Dèce: Gaius Valens Hostilianus Messius Quintus Caesar
• 251, appointed Emperor by Trébonien Galle: Imperator Caesar Caius Valens Hostilianus Messius Quintus Pius Felix Invictus Augustus