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 (–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) ()
  • Decimus Junius Silanus (translator of Mago) ()
  • Decimus Laberius (–43 BC), Roman eques and writer
  • Decimus Laelius (), Roman lawyer and tribune of the plebs
  • Decimus Laelius Balbus, consul in 6 BC
  • Decimus Valerius Asiaticus (–47 AD), Roman senator
  • Decimus Valerius Asiaticus (Legatus) (35-after 69 AD), Roman senator, Legatus of Gallia Belgica
  • Ausonius (Decimus Magnus Ausonius, –), Roman poet and rhetorician
  • Balbinus (Decimus Caelius Calvinus Balbinus, –238), Roman emperor in 238
  • Clodius Albinus (–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