Decimus
Decimus may refer to:

Romen praenomen
Decimus (praenomen)
Decimus Carfulenus (died 43 BC), Roman statesman
Decimus Haterius Agrippa (died 32 AD), consul in 22 AD
Decimus Junius Brutus (consul 77 BC)
Decimus Junius Brutus Albinus (c. 81 BC–43 BC), Roman politician and general, assassin of Julius Caesar
Decimus Junius Brutus Callaicus (180 BC–113 BC), Roman politician and general
Decimus Junius Silanus Torquatus (16 AD–64 AD), consul in AD 53
Decimus Junius Silanus (consul) (fl. 70–62 BC)
Decimus Junius Silanus (translator of Mago) (fl. 2nd century BC)
Decimus Laberius (c. 105 BC–43 BC), Roman eques and writer
Decimus Laelius (fl. 1st century BC), Roman lawyer and tribune of the plebs
Decimus Laelius Balbus, consul in 6 BC
Decimus Valerius Asiaticus (c. 5 BC–47 AD), Roman senator
Decimus Valerius Asiaticus (Legatus) (35-after 69 AD), Roman senator, Legatus of Gallia Belgica
Ausonius (Decimus Magnus Ausonius, c. 310–c. 395), Roman poet and rhetorician
Balbinus (Decimus Caelius Calvinus Balbinus, c. 165–238), Roman emperor in 238
Clodius Albinus (c. 150–197), Roman usurper
Juvenal (Decimus Junius Juvenalis), poet of the 1st century AD

Given name
Decimus Burton (1800–1881), English architect
Decimus Govett (1827–1912), Anglican priest

Pen-name
Thomas Chatterton (1752–1780), English poet