Gaius Messius Quintus Traianus Decius (c. 201  June 251), sometimes translated as Trajan Decius, was Roman emperor from 249 to 251.

Roman emperor
ReignSeptember 249 – June 251
PredecessorPhilip the Arab
SuccessorTrebonianus Gallus and Hostilian
Co-emperorHerennius Etruscus (251)
Bornc. 201
Budalia (present day Martinci, Serbia)
Died251 (aged 4950)
Abrittus (present day Razgrad, Bulgaria)
SpouseHerenia Etruscilla
IssueHerennius Etruscus and Hostilian
Gaius Messius Quintus Decius Valerinus[1]
Gaius Messius Quintus Traianus Decius
ReligionRoman polytheism

A distinguished politician during the reign of Philip the Arab, Decius was proclaimed emperor by his troops after putting down a rebellion in Moesia. In 249, he defeated and killed Philip near Verona and was recognized as emperor by the Senate afterwards. During his reign, he attempted to strengthen the Roman state and its religion, leading to the Decian persecution, where a number of prominent Christians (including Pope Fabian) were put to death.

In the last year of his reign, Decius co-ruled with his son Herennius Etruscus, until they were both killed by the Goths in the Battle of Abritus.